Patent Publication Number: US-2021180653-A1

Title: Tolerance ring with desired slip performance, assembly, and method of making and using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 62/948,133, entitled “TOLERANCE RING WITH DESIRED SLIP PERFORMANCE, ASSEMBLY, AND METHOD OF MAKING AND USING THE SAME,” by Andrew R. SLAYNE et al., filed Dec. 13, 2019, which is assigned to the current assignee hereof and incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure generally relates to tolerance rings and, in particular, to tolerance rings that modify torque assemblies. 
     BACKGROUND 
     Commonly, tolerance rings constrain movement between relatively moving parts, such as rotating inner components in bores within outer components. Further, tolerance rings have a number of other potential advantages, such as compensating tolerances for parts that are not machined to exact dimensions, compensating for different coefficients of expansion between the parts, allowing rapid assembly, and durability. One type tolerance ring may be located in a gap between the outer surface of an inner component and the inner surface of the bore of an outer component to transmit torque within an assembly. Exemplary assemblies may include door, hood, tailgate, and engine compartment hinges, seats, steering columns, flywheels, driveshaft assemblies, or may include other assemblies notably those used in automotive applications. Sometimes, there exists a need to have desired slip at desired surfaces of the inner component and the outer component in such an assembly. Therefore, there exists is an ongoing need for improved tolerance rings that provide improved slip performance while maintaining appropriate tolerance compensation and providing a longer lifetime of the assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. 
         FIG. 1  includes a method of producing a tolerance ring in accordance with an embodiment; 
         FIG. 2A  includes a cross-sectional view of one embodiment of a tolerance ring in accordance with an embodiment; 
         FIG. 2B  includes a cross-sectional view of one embodiment of a tolerance ring in accordance with an embodiment; 
         FIG. 2C  includes a cross-sectional view of one embodiment of a tolerance ring in accordance with an embodiment; 
         FIG. 2D  includes a cross-sectional view of one embodiment of a tolerance ring in accordance with an embodiment; 
         FIG. 3A  includes a perspective view of one embodiment of a tolerance ring constructed in accordance with the invention; 
         FIG. 3B  includes a top view of one embodiment of a tolerance ring constructed in accordance with the invention; 
         FIG. 3C  includes a side view of one embodiment of a tolerance ring constructed in accordance with the invention; 
         FIG. 4  includes a perspective view of another embodiment of a tolerance ring constructed in accordance with the invention; 
         FIG. 5A  includes an axial sectional view of the tolerance ring of  FIG. 3A  in an assembly; 
         FIG. 5B  includes a radial sectional view of the tolerance ring of  FIG. 3A  in the assembly; 
         FIG. 6  includes an end view of a tolerance ring in an assembly in accordance with an embodiment; 
         FIG. 7  includes a sample graph of the torque (N·m) as a function of function of the time (s) when testing a tolerance ring in accordance with an embodiment; 
         FIG. 8  includes multiple of a control tolerance ring in a free state condition or in an assembly; and 
         FIG. 9  includes multiple of an experimental tolerance ring in a free state condition or in an assembly in accordance with an embodiment. 
     
    
    
     Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention. The use of the same reference symbols in different drawings indicates similar or identical items. 
     DESCRIPTION OF THE DRAWING(S) 
     The following description in combination with the figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other embodiments can be used based on the teachings as disclosed in this application. 
     The terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or assembly that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or assembly. Further, unless expressly stated to the contrary, “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). 
     Also, the use of “a” or “an” is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one, at least one, or the singular as also including the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single embodiment is described herein, more than one embodiment may be used in place of a single embodiment. Similarly, where more than one embodiment is described herein, a single embodiment may be substituted for that more than one embodiment. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing acts are conventional and may be found in textbooks and other sources within the tolerance ring and tolerance ring assembly arts. 
     For purposes of illustration,  FIG. 1  includes a diagram showing a forming process  10  for forming a tolerance ring. The forming process  10  may include a first step  12  of providing a material or composite material including a substrate. Optionally, the forming process  10  may further include a second step  14  of curling the ends of the material or composite material to form a tolerance ring. 
       FIG. 2A  includes an illustration of a material  1000  that may be formed into the tolerance ring of the first step  12  of the forming process  10 . The tolerance ring may include a substrate  119 . In an embodiment, the substrate  119  can at least partially include a metal. According to certain embodiments, the metal may include iron, copper, titanium, tin, aluminum, alloys thereof, or may be another type of metal. More particularly, the substrate  119  can at least partially include a steel, such as, a stainless steel, carbon steel, or spring steel. For example, the substrate  119  can at least partially include a 301 stainless steel. The 301 stainless steel may be annealed, ¼ hard, ½ hard, ¾ hard, or full hard. Moreover, the steel can include stainless steel including chrome, nickel, or a combination thereof. In an embodiment, the substrate  119  may include a woven mesh or an expanded metal grid. The woven mesh or expanded metal grid can include a metal or metal alloy such as aluminum, steel, stainless steel, bronze, or the like. Alternatively, the woven mesh can be a woven polymer mesh. In an alternate embodiment, the substrate  119  may not include a mesh or grid. Further, the substrate  119  can include a Vickers pyramid number hardness, VPN, which can be ≥350, such as ≥375, ≥400, ≥425, or ≥450. VPN can also be ≤500, ≤475, or ≤450. VPN can also be within a range between, and including, any of the VPN values described herein. In another aspect, the substrate  119  can be treated to increase its corrosion resistance. In particular, the substrate  119  can be passivated. For example, the substrate  119  can be passivated according to the ASTM standard A967. The substrate  119  may be formed by at least one of chamfering, turning, reaming, forging, extruding, molding, sintering, rolling, or casting. 
     The substrate  119  can have a thickness Ts of between about 1 micron to about 1000 microns, such as between about 50 microns and about 500 microns, such as between about 100 microns and about 250 microns, such as between about 75 microns and about 150 microns. In a number of embodiments, the substrate  119  may have a thickness Ts of between about 50 and 1000 microns. It will be further appreciated that the thickness Ts of the substrate  119  may be any value between any of the minimum and maximum values noted above. The thickness of the substrate  119  may be uniform, i.e., a thickness at a first location of the substrate  119  can be equal to a thickness at a second location therealong. The thickness of the substrate  119  may be non-uniform, i.e., a thickness at a first location of the substrate  119  can be different than a thickness at a second location therealong. 
       FIG. 2B  includes an illustration of a composite material  1001 , alternative to the material  1000 , that may be formed into the tolerance ring of the first step  12  of the forming process  10 . For purposes of illustration,  FIG. 2B  shows the layer by layer configuration of a composite material  1001  of the tolerance ring. In a number of embodiments, the composite material  1001  may include substrate  119  (as mentioned above) and low friction layer  104  coupled to or overlying the substrate  119 . In a more particular embodiment, the composite material  1001  may include a substrate  119  and a plurality of one low friction layers  104  overlying the substrate  119 . As shown in  FIG. 2B , the low friction layer  104  can be coupled to at least a portion of the substrate  119 . In a particular embodiment, the low friction layer  104  can be coupled to a surface of the substrate  119  so as to form an interface with another surface of another component. The low friction layer  104  can be coupled to the radially inner surface of the substrate  119 . Alternatively, the low friction layer  104  can be coupled to the radially outer surface of the substrate  119 . 
     In a number of embodiments, the low friction layer  104  can include a low friction material. Low friction materials may include, for example, a polymer, such as a polyketone, a polyaramid, a polyphenylene sulfide, a polyethersulfone, a polyphenylene sulfone, a polyamideimide, ultra high molecular weight polyethylene, a fluoropolymer, a polybenzimidazole, a polyacetal, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), a polyimide (PI), polyetherimide, polyetheretherketone (PEEK), polyethylene (PE), a polysulfone, a polyamide (PA), polyphenylene oxide, polyphenylene sulfide (PPS), a polyurethane, a polyester, a liquid crystal polymer (LCP), or any combination thereof. In an example, the low friction layer  104  includes polyketone, such as polyether ether ketone (PEEK), polyether ketone, polyether ketone ketone, polyether ketone ether ketone, a derivative thereof, or a combination thereof. In an additional example, the low friction layer  104  may include an ultra high molecular weight polyethylene. In another example, the low friction layer  104  may include a fluoropolymer including fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), perfluoroalkoxy (PFA), a terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride (THV), polychlorotrifluoroethylene (PCTFE), ethylene tetrafluoroethylene copolymer (ETFE), or ethylene chlorotrifluoroethylene copolymer (ECTFE). The low friction layer  104  may include a solid based material including lithium soap, graphite, boron nitride, molybdenum disulfide, tungsten disulfide, polytetrafluoroethylene, carbon nitride, tungsten carbide, or diamond like carbon, a metal (such as aluminum, zinc, copper, magnesium, tin, platinum, titanium, tungsten, iron, bronze, steel, spring steel, stainless steel), a metal alloy (including the metals listed), an anodized metal (including the metals listed) or any combination thereof. Fluoropolymers may be used according to particular embodiments. In an embodiment, the low friction layer  104  may include a woven mesh or an expanded metal grid. The woven mesh or expanded metal grid can include a metal or metal alloy such as aluminum, steel, stainless steel, bronze, or the like. Alternatively, the woven mesh can be a woven polymer mesh. In an alternate embodiment, the low friction layer  104  may not include a mesh or grid. 
     In a number of embodiments, the low friction layer  104  may further include fillers, including glass fibers, carbon fibers, silicon, PEEK, aromatic polyester, carbon particles, bronze, fluoropolymers, thermoplastic fillers, aluminum oxide, polyamideimide (PAI), PPS, polyphenylene sulfone (PPSO2), LCP, aromatic polyesters, molybdenum disulfide, tungsten disulfide, graphite, grapheme, expanded graphite, boron nitrade, talc, calcium fluoride, or any combination thereof. Additionally, the filler can include alumina, silica, titanium dioxide, calcium fluoride, boron nitride, mica, Wollastonite, silicon carbide, silicon nitride, zirconia, carbon black, pigments, or any combination thereof. Fillers can be in the form of beads, fibers, powder, mesh, or any combination thereof. The fillers may be at least 10 wt % based on the total weight of the low friction layer, such as at least 15 wt %, 20 wt %, 25 wt % or even 30 wt %. 
     In an embodiment, the low friction layer  104  can have a thickness T LFL  of between about 1 micron to about 500 microns, such as between about 10 microns and about 250 microns, such as between about 30 microns and about 150 microns, such as between about 40 microns and about 100 microns. In a number of embodiments, the low friction layer  104  may have a thickness T LFL  of between about 50 and 250 microns. It will be further appreciated that the thickness T LFL  of the low friction layer  104  may be any value between any of the minimum and maximum values noted above. The thickness of the low friction layer  104  may be uniform, i.e., a thickness at a first location of the low friction layer  104  can be equal to a thickness at a second location therealong. The thickness of the low friction layer  104  may be non-uniform, i.e., a thickness at a first location of the low friction layer  104  can be different than a thickness at a second location therealong. It can be appreciated that different low friction layers  104  may have different thicknesses. The low friction layer  104  may overlie one major surface of the substrate  119 , shown, or overlie both major surfaces. The substrate  119  may be at least partially encapsulated by the low friction layer  104 . That is, the low friction layer  104  may cover at least a portion of the substrate  119 . Axial surfaces of the substrate  119  may be exposed from the low friction layer  104 . 
       FIG. 2C  includes an illustration of an alternative embodiment of the composite material  1002 , alternative to the materials  1000 ,  1001 , that may be formed into the tolerance ring of the first step  12  of the forming process  10 . For purposes of illustration,  FIG. 2C  shows the layer by layer configuration of a composite material  1002  of the tolerance ring. According to this particular embodiment, the composite material  1002  may be similar to the composite material  1001  of  FIG. 2B , except this composite material  1002  may also include at least one adhesive layer  121  that may couple the low friction layer  104  to the substrate  119  and a low friction layer  104 . In another alternate embodiment, the substrate  119 , as a solid component, woven mesh or expanded metal grid, may be embedded between at least one adhesive layer  121  included between the low friction layer  104  and the substrate  119 . 
     The adhesive layer  121  may include any known adhesive material common to the ring arts including, but not limited to, fluoropolymers, epoxy resins, polyimide resins, polyether/polyamide copolymers, ethylene vinyl acetates, ethylene tetrafluoroethylene (ETFE), ETFE copolymer, perfluoroalkoxy (PFA), or any combination thereof. 
     Additionally, the adhesive can include at least one functional group selected from —C═O, —C—O—R, —COH, —COOH, —COOR, —CF 2 ═CF—OR, or any combination thereof, where R is a cyclic or linear organic group containing between 1 and 20 carbon atoms. Additionally, the adhesive can include a copolymer. 
     Filler particles (functional and/or nonfunctional) may be added in to the adhesive layer  121  such as carbon fillers, carbon fibers, carbon particles, graphite, metallic fillers such as bronze, aluminum, and other metals and their alloys, metal oxide fillers, metal coated carbon fillers, metal coated polymer fillers, or any combination thereof. 
     In an embodiment, the hot melt adhesive can have a melting temperature of not greater than 250° C., such as not greater than 220° C. In another embodiment, the adhesive may break down above 200° C., such as above 220° C. In further embodiments, the melting temperature of the hot melt adhesive can be higher than 250° C. or even higher than 300° C. The adhesive layer  121  can have a thickness T AL  of between about 1 micron to about 500 microns, such as between about 10 microns and about 250 microns, such as between about 30 microns and about 150 microns, such as between about 40 microns and about 100 microns. In a number of embodiments, the adhesive layer  121  may have a thickness T AL  of between about 50 and 250 microns. In a number of embodiments, the adhesive layer  121  may have a thickness T AL  of between about 80 and 120 microns. It will be further appreciated that the thickness T AL  of the adhesive layer  121  may be any value between any of the minimum and maximum values noted above. The thickness of the adhesive layer  121  may be uniform, i.e., a thickness at a first location of the adhesive layer  121  can be equal to a thickness at a second location therealong. The thickness of the adhesive layer  121  may be non-uniform, i.e., a thickness at a first location of the adhesive layer  121  can be different than a thickness at a second location therealong. 
       FIG. 2D  includes an illustration of an alternative embodiment of the composite material  1003 , alternative to the materials  1000 ,  1001 ,  1002 , that may be formed into the tolerance ring of the first step  12  of the forming process  10 . For purposes of illustration,  FIG. 2D  shows the layer by layer configuration of a composite material  1003  of the tolerance ring. According to this particular embodiment, the composite material  1003  may be similar to the composite material  1002  of  FIG. 2C , except this composite material  1003  may also include at least one corrosion protection layer  704 ,  705 , and  708 , and a corrosion resistant coating  1124  that can include an adhesion promoter layer  127  and an epoxy layer  129  that may couple to the substrate  119  and a low friction layer  104 . 
     The substrate  119  may be coated with corrosion protection layers  704  and  705  including corrosion protection material to prevent corrosion of the composite material  1003  prior to processing. Additionally, a corrosion protection layer  708  can be applied over layer  704 . Each of layers  704 ,  705 , and  708  can have a thickness of about 1 to 50 microns, such as about 7 to 15 microns. Layers  704  and  705  can include corrosion protection materials including a phosphate of zinc, iron, manganese, or any combination thereof, or a nano-ceramic layer. Further, layers  704  and  705  can include corrosion protection materials including functional silanes, nano-scaled silane based primers, hydrolyzed silanes, organosilane adhesion promoters, solvent/water based silane primers, chlorinated polyolefins, passivated surfaces, commercially available zinc (mechanical/galvanic) or zinc-nickel coatings, or any combination thereof. Layer  708  can include functional silanes, nano-scaled silane based primers, hydrolyzed silanes, organosilane adhesion promoters, solvent/water based silane primers. Corrosion protection layers  704 ,  1706 , and  708  can be removed or retained during processing. 
     As stated above, the composite material  1003  may further include a corrosion resistant coating  125 . The corrosion resistant coating  125  can have a thickness of about 1 to 50 microns, such as about 5 to 20 microns, and such as about 7 to 15 microns. The corrosion resistant coating  125  can include an adhesion promoter layer  127  and an epoxy layer  129 . The adhesion promoter layer  127  can include corrosion protection materials including phosphate of zinc, iron, manganese, tin, or any combination thereof, or a nano-ceramic layer. The adhesion promoter layer  127  can include corrosion protection materials including functional silanes, nano-scaled silane based layers, hydrolyzed silanes, organosilane adhesion promoters, solvent/water based silane primers, chlorinated polyolefins, passivated surfaces, commercially available zinc (mechanical/galvanic) or Zinc-Nickel coatings, or any combination thereof. The adhesion promoter layer  127  can be applied by spray coating, e-coating, dip spin coating, electrostatic coating, flow coating, roll coating, knife coating, coil coating, or the like. 
     The epoxy layer  129  can be corrosion protection materials including a thermal cured epoxy, a UV cured epoxy, an IR cured epoxy, an electron beam cured epoxy, a radiation cured epoxy, or an air cured epoxy. Further, the epoxy layer  129  can include corrosion protection materials including polyglycidylether, diglycidylether, bisphenol A, bisphenol F, oxirane, oxacyclopropane, ethylenoxide, 1,2-epoxypropane, 2-methyloxirane, 9,10-epoxy-9,10-dihydroanthracene, or any combination thereof. The epoxy layer  129  can further include a hardening agent. The hardening agent can include amines, acid anhydrides, phenol novolac hardeners such as phenol novolac poly[N-(4-hydroxyphenyl)maleimide] (PHPMI), resole phenol formaldehydes, fatty amine compounds, polycarbonic anhydrides, polyacrylate, isocyanates, encapsulated polyisocyanates, boron trifluoride amine complexes, chromic-based hardeners such as chromium, polyamides, or any combination thereof. Generally, acid anhydrides can conform to the formula R—C═O—O—C═O—R′ where R can be C X H Y X Z A U  as described above. Amines can include aliphatic amines such as monoethylamine, diethylenetriamine, triethylenetetraamine, and the like, alicyclic amines, aromatic amines such as cyclic aliphatic amines, cyclo aliphatic amines, amidoamines, polyamides, dicyandiamides, imidazole derivatives, and the like, or any combination thereof. Generally, amines can be primary amines, secondary amines, or tertiary amines conforming to the formula R 1 R 2 R 3 N where R can be C X H Y X Z A U  as described above. In an embodiment, the epoxy layer  129  can include fillers to improve the conductivity, such as carbon fillers, carbon fibers, carbon particles, graphite, metallic fillers such as bronze, aluminum, and other metals and their alloys, metal oxide fillers, metal coated carbon fillers, metal coated polymer fillers, or any combination thereof. The conductive fillers can allow current to pass through the epoxy coating and can increase the conductivity of the composite material as compared to a composite material without conductive fillers. In an embodiment, the epoxy layer  129  can be applied by spray coating, e-coating, dip spin coating, electrostatic coating, flow coating, roll coating, knife coating, coil coating, or the like. Additionally, the epoxy layer  129  can be cured, such as by thermal curing, UV curing, IR curing, electron beam curing, irradiation curing, or any combination thereof. Preferably, the curing can be accomplished without increasing the temperature of the component above the breakdown temperature of any of the low friction layer  104 , the adhesive layer  121 , the substrate  119 , or the adhesion promoter layer  127 . Accordingly, the epoxy may be cured below about 250° C., even below about 200° C. 
     In an embodiment, under step  12  of  FIG. 1 , any of the layers on the material or composite material  1000 ,  1001 ,  1002 ,  1003 , as described above, can each be disposed in a roll and peeled therefrom to join together under pressure, at elevated temperatures (hot or cold pressed or rolled), by an adhesive, or by any combination thereof. Any of the layers of the material or composite material  1000 ,  1001 ,  1002 ,  1003 , as described above, may be laminated together such that they at least partially overlap one another. Any of the layers on the material or composite material  1000 ,  1001 ,  1002 ,  1003 , as described above, may be applied together using coating technique, such as, for example, physical or vapor deposition, spraying, plating, powder coating, or through other chemical or electrochemical techniques. In a particular embodiment, the low friction layer  104  may be applied by a roll-to-roll coating process, including for example, extrusion coating. The low friction layer  104  may be heated to a molten or semi-molten state and extruded through a slot die onto a major surface of the substrate  119 . In an embodiment, the material or composite material  1000 ,  1001 ,  1002 ,  1003 , may be a single unitary strip of material. 
     In other embodiments, under step  12  of  FIG. 1 , any of the layers on the material or composite material  1000 ,  1001 ,  1002 ,  1003 , as described above, may be applied by a coating technique, such as, for example, physical or vapor deposition, spraying, plating, powder coating, or through other chemical or electrochemical techniques. In a particular embodiment, the low friction layer  104  may be applied by a roll-to-roll coating process, including for example, extrusion coating. The low friction layer  104  may be heated to a molten or semi-molten state and extruded through a slot die onto a major surface of the substrate  119 . In another embodiment, the low friction layer  104  may be cast or molded. 
     In an embodiment, the low friction layer  104  or any layers can be glued to the substrate  119  using the melt adhesive layer  121  to form a laminate. In an embodiment, any of the intervening or outstanding layers on the material or composite material  1000 ,  1001 ,  1002 ,  1003 , may form the laminate. The laminate can be cut into strips or blanks that can be formed into the tolerance ring. The cutting of the laminate may include use of a stamp, press, punch, saw, or may be machined in a different way. Cutting the laminate can create cut edges including an exposed portion of the substrate  119 . 
     In an embodiment, under step  14  of  FIG. 1 , the blanks can be formed into the tolerance ring by curling the ends of the laminate strip or blank. The tolerance ring may be formed by stamp, press, punch, saw, rolling, flanging, deep-drawing, or may be machined in a different way. 
     After shaping the semi-finished tolerance ring, the semi-finished tolerance ring may be cleaned to remove any lubricants and oils used in the forming and shaping process. Additionally, cleaning can prepare the exposed surface of the load bearing substrate for the application of the coating. Cleaning may include chemical cleaning with solvents and/or mechanical cleaning, such as ultrasonic cleaning. 
       FIG. 3A  depicts a tolerance ring  100  including one embodiment formed from a blank of material or composite material  1000 ,  1001 ,  1002 ,  1003  as described above. The tolerance ring  100  includes a sidewall  102 . The sidewall  102  may be formed from a blank as described above and may include a substrate  119  (e.g. spring steel) that may be curved into a ring-like (substantially annular or generally cylindrical) shape about a central axis  3000 , forming an aperture  115 . The ends of the sidewall  102  may not meet (e.g., it may be formed as a split ring), thereby leaving an axial gap  106  adjacent the circumference of the sidewall  102 . In other embodiments, the sidewall may be curved so that the ends overlap with one another. In yet further embodiments, as shown best in  FIG. 3B , the sidewall  102  may be a continuous, unbroken ring. The sidewall  102  may further include a low friction layer  104  that conforms to the shape of the sidewall  102 , as formed as a low friction layer  104  from the blank of composite material  1000 ,  1001 ,  1002 ,  1003  as described above. The tolerance ring  100  and/or sidewall  102  may have a first axial end  120 , and a second axial end  122 . The tolerance ring  100  and/or sidewall  102  may have an inner surface  130 , and an outer surface  132 . The inner surface  130  of the tolerance ring  100  and/or sidewall  102  may have a low friction layer  104  that conforms to the shape of the sidewall, as formed from the composite material  1000 ,  1001 ,  1002 ,  1003  as described above. 
     The tolerance ring  100  may have a plurality of spaced projections  108  that extend radially inward or outward from the outer surface  132  of the tolerance ring  100 . The projections may be capable of deformation upon compression. The projections  108  may be formed via stamping (e.g., pressed using a suitably shaped mold, rotary wave forming, etc.). Optionally, there may be a flat, circumferentially-extending rim  109  of composite material located on at least one axial end of the projections  108 . Alternatively, the axial ends of the projections  108  may be disposed at the first axial end  120  or the second axial  122  of the tolerance ring  100 . Optionally, each projection  108  may also be separated from its neighboring projections  108  by an unformed section  110  of the tolerance ring  100 , which may be contiguously formed with rims  109  and spaced circumferentially between a first pair of adjacent projections  108 . The projections  108  may include axially-elongated circumferential ridges extending in the radial direction that may be similar in shape to waves used on conventional tolerance rings. The peak  113  of each ridge may be rounded, and the axial ends of each ridge terminate at a pair of tapered shoulders  111 . Optionally, the tolerance ring  100  may include an unformed region  114  on the opposite surface as surface that the projections  108  extend radially from. For example, as shown in  FIG. 3A , the unformed region  114  may be on the inner surface  130  while the projections  108  extend radially outwardly along the outer surface  132 . The unformed region  114  may include no projections and be contiguous with the sidewall  102 . 
     As shown in  FIGS. 3A-3C , the tolerance ring  100  may include a plurality of projections  108  of different types. The tolerance ring  100  may include a first type of projection  108   a  and a second type of projection  108   b . The first type of projection  108   a  may have a radial height, H PA . For purposes of embodiments described herein, the radial height, H PA , of the first type of projection  108   a  is the distance from the peak  113  of the projection  108   a  to the unformed region  114  of the sidewall  102 , as shown best in  FIG. 3B . According to certain embodiment, the radial height, H PA , of the first type of projection  108   a  may be at least about 0.1 mm or at least about 0.2 mm or at least about 0.3 mm or at least about 0.4 mm or even at least about 0.5 mm. According to still other embodiments, the radial height, H PA , of the first type of projection  108   a  may be not greater than about 10 mm, such as not greater than 8 mm, not greater than 6 mm, 5 mm, 3 mm, 1 mm, 0.9 mm or even not greater than about 0.8 mm. In a number of embodiments, the radial height, H PA , of the first type of projection  108   a  may be in the range of at least about 0.1 mm to no greater than about 1.5 mm. It will be appreciated that the radial height, H PA , of the first type of projection  108   a  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the radial height, H PA , of the first type of projection  108   a  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that radial height, H PA , of the first type of projection  108   a  may vary along its circumference and may vary across a plurality of tolerance rings. 
     The first type of projection  108   a  may have a circumferential width, W PA . For purposes of embodiments described herein, the circumferential width, W PA , of the first type of projection  108   a  is the distance from the edge of one unformed section  110  adjacent to the first type of projection  108   a  to the unformed section  110  on the circumferentially opposite side of the first type of projection  108   a , as shown best in  FIG. 3B . According to certain embodiment, the circumferential width, W PA , of the first type of projection  108   a  may be at least about 0.1 mm or at least about 0.2 mm or at least about 0.3 mm or at least about 0.4 mm or even at least about 0.5 mm. According to still other embodiments, the circumferential width, W PA , of the first type of projection  108   a  may be not greater than about 20 mm, such as, not greater than about 15 mm, 10 mm, 5 mm, 1 mm, 0.9 mm or even not greater than about 0.8 mm. In a number of embodiments, the circumferential width, W PA , of the first type of projection  108   a  may be in the range of at least about 1 mm to no greater than about 10 mm. It will be appreciated that the circumferential width, W PA , of the first type of projection  108   a  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the circumferential width, W PA , of the first type of projection  108   a  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that circumferential width, W PA , of the first type of projection  108   a  may vary along its circumference and may vary across a plurality of tolerance rings. 
     The first type of projection  108   a  may have a shoulder length, L SA . For purposes of embodiments described herein, the shoulder length, L SA , of the first type of projection  108   a  is the distance from the rim  109  or axial end  120 ,  122  of the tolerance ring  100  to the edge of the top of the shoulder  111  at the peak  113 , as shown best in  FIG. 3C . According to certain embodiment, the shoulder length, L SA , of the first type of projection  108   a  may be at least about 0.1 mm or at least about 0.2 mm or at least about 0.3 mm or at least about 0.4 mm or even at least about 0.5 mm. According to still other embodiments, the shoulder length, L SA , of the first type of projection  108   a  may be not greater than about 5 mm, such as not greater than 1 mm, not greater than about 0.9 mm or even not greater than about 0.8 mm. In a number of embodiments, the shoulder length, L SA , of the first type of projection  108   a  may be in the range of at least about 0.3 mm to no greater than about 2 mm. It will be appreciated that the shoulder length, L SA , of the first type of projection  108   a  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the shoulder length, L SA , of the first type of projection  108   a  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that shoulder length, L SA , of the first type of projection  108   a  may vary along its circumference and may vary across a plurality of tolerance rings. 
     The first type of projection  108   a  may have a slope of the ridge S RPA . For purposes of embodiments described herein, the slope of the ridge, S RPA , of the first type of projection  108   a  is the radial height, H PA , of the first type of projection  108   a  divided by half of the circumferential width, W PA , of the first type of projection  108   a . According to certain embodiment, the slope of the ridge, S RPA , of the first type of projection  108   a  may be at least about 0.1 or at least about 0.2 or at least about 0.3 or at least about 0.4, at least about 0.5, at least about 1, at least about 2, at least about 4, at least about 6, or even at least about 10. According to still other embodiments, the slope of the ridge, S RPA , of the first type of projection  108   a  may be not greater than about 50, such as, not greater than about 20 or even not greater than about 10. In a number of embodiments, the slope of the ridge, S RPA , of the first type of projection  108   a  may be in the range of at least about 0.02 to no greater than about 3. It will be appreciated that the slope of the ridge, S RPA , of the first type of projection  108   a  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the slope of the ridge, S RPA , of the first type of projection  108   a  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that slope of the ridge, S RPA , of the first type of projection  108   a  may vary along the circumferential length of the first type of projection  108   a  and may vary across a plurality of tolerance rings. 
     In a particular embodiment, the first type of projections  108   a  of tolerance ring  100  can have a radial stiffness of about 50 to about 6000 N. Moreover, the radial stiffness of the first type of projections  108   a  can also be within a range between and including any of the values described above. Radial stiffness of the first type of projections  108   a  of the tolerance ring  100  can be measured by measuring the radial force required to compress the first type of projections  108   a  for a component (inner or outer component as described below) clearance in the circumferential direction. 
     The second type of projection  108   b  may have a radial height, H PB . For purposes of embodiments described herein, the radial height, H PB , of the second type of projection  108   b  is the distance from the peak  113  of the projection  108   b  to the unformed region  114  of the sidewall  102 , as shown best in  FIG. 3B . According to certain embodiment, the radial height, H PB , of the second type of projection  108   b  may be at least about 0.1 mm or at least about 0.2 mm or at least about 0.3 mm or at least about 0.4 mm or even at least about 0.5 mm. According to still other embodiments, the radial height, H PB , of the second type of projection  108   b  may be not greater than about 10 mm, such as not greater than 8 mm, not greater than 6 mm, 5 mm, 3 mm, 1 mm, 0.9 mm or even not greater than about 0.8 mm. In a number of embodiments, the radial height, H PB , of the second type of projection  108   b  may be in the range of at least about 0.1 mm to no greater than about 1.5 mm. It will be appreciated that the radial height, H PB , of the second type of projection  108   b  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the radial height, H PB , of the second type of projection  108   b  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that radial height, H PB , of the second type of projection  108   b  may vary along its circumference and may vary across a plurality of tolerance rings. In a number of embodiments, the first type of projections  108   a  may have a different radial height versus the second type of projections  108   b . This may result in the first type of projections  108   a  having different properties or behaviors versus the second type of projections  108   b.    
     The second type of projection  108   b  may have a circumferential width, W PB . For purposes of embodiments described herein, the circumferential width, W PB , of the second type of projection  108   b  is the distance from the edge of one unformed section  110  adjacent to the second type of projection  108   b  to the unformed section  110  on the circumferentially opposite side of the second type of projection  108   b , as shown best in  FIG. 3B . According to certain embodiment, the circumferential width, W PB , of the second type of projection  108   b  may be at least about 0.1 mm or at least about 0.2 mm or at least about 0.3 mm or at least about 0.4 mm or even at least about 0.5 mm. According to still other embodiments, the circumferential width, W PB , of the second type of projection  108   b  may be not greater than about 20 mm, such as, not greater than about 15 mm, 10 mm, 5 mm, 1 mm, 0.9 mm or even not greater than about 0.8 mm. In a number of embodiments, the circumferential width, W PB , of the second type of projection  108   b  may be in the range of at least about 1 mm to no greater than about 10 mm. It will be appreciated that the circumferential width, W PB , of the second type of projection  108   b  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the circumferential width, W PB , of the second type of projection  108   b  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that circumferential width, W PB , of the second type of projection  108   b  may vary along its circumference and may vary across a plurality of tolerance rings. In a number of embodiments, the first type of projections  108   a  may have a different circumferential width versus the second type of projections  108   b . This may result in the first type of projections  108   a  having different properties or behaviors versus the second type of projections  108   b.    
     The second type of projection  108   b  may have a shoulder length, L SB . For purposes of embodiments described herein, the shoulder length, L SB , of the second type of projection  108   b  is the distance from the rim  109  or axial end  120 ,  122  of the tolerance ring  100  to the edge of the top of the shoulder  111  at the peak  113 , as shown best in  FIG. 3C . According to certain embodiment, the shoulder length, L SB , of the second type of projection  108   b  may be at least about 0.1 mm or at least about 0.2 mm or at least about 0.3 mm or at least about 0.4 mm or even at least about 0.5 mm. According to still other embodiments, the shoulder length, L SB , of the second type of projection  108   b  may be not greater than about 5 mm, such as not greater than about 1 mm, not greater than about 0.9 mm or even not greater than about 0.8 mm. In a number of embodiments, the shoulder length, L SB , of the second type of projection  108   b  may be in the range of at least about 0.3 mm to no greater than about 2 mm. It will be appreciated that the shoulder length, L SB , of the second type of projection  108   b  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the shoulder length, L SB , of the second type of projection  108   b  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that shoulder length, L SB , of the second type of projection  108   b  may vary along its circumference and may vary across a plurality of tolerance rings. In a number of embodiments, the first type of projections  108   a  may have a different shoulder length versus the second type of projections  108   b . This may result in the first type of projections  108   a  having different properties or behaviors versus the second type of projections  108   b.    
     The second type of projection  108   b  may have a slope of the ridge S RPB . For purposes of embodiments described herein, the slope of the ridge, S RPB , of the second type of projection  108   b  is the radial height, H PB , of the second type of projection  108   b  divided by half of the circumferential width, W PB , of the second type of projection  108   b . According to certain embodiment, the slope of the ridge, S RPB , of the second type of projection  108   b  may be at least about 0.1 or at least about 0.2 or at least about 0.3 or at least about 0.4, at least about 0.5, at least about 1, at least about 2, at least about 4, at least about 6, or even at least about 10. According to still other embodiments, the slope of the ridge, S RPB , of the second type of projection  108   b  may be not greater than about 50, such as, not greater than about 20 or even not greater than about 10. A number of embodiments, the slope of the ridge, S RPB , of the second type of projection  108   b  may be in the range of at least about 0.02 to no greater than about 3. It will be appreciated that the slope of the ridge, S RPB , of the second type of projection  108   b  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the slope of the ridge, S RPB , of the second type of projection  108   b  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that slope of the ridge, S RPB , of the second type of projection  108   b  may vary along the circumferential length of the second type of projection  108   b  and may vary across a plurality of tolerance rings. In a number of embodiments, the first type of projections  108   a  may have a different slope of at least one ridge of the projection versus the second type of projections  108   b . This may result in the first type of projections  108   a  having different properties or behaviors versus the second type of projections  108   b.    
     In a particular embodiment, the second type of projection  108   b  of tolerance ring  100  can have a radial stiffness of about 50 to about 6000 N. Moreover, the radial stiffness of the second type of projection  108   b  can also be within a range between and including any of the values described above. Radial stiffness of the second type of projection  108   b  of the tolerance ring  100  can be measured by measuring the radial force required to compress the second type of projection  108   b  for a component (inner or outer component as described below) clearance in the circumferential direction. In a number of embodiments, the torque of the second type of projection  108   b  may be about 2500 N/mm. 
       FIG. 4  depicts another embodiment of a tolerance ring  200 . In a similar way to  FIG. 3 , the tolerance ring  200  and/or sidewall  202  may have a first axial end  220 , and a second axial end  222 , and be formed about a central axis  3000 , forming an aperture  215 . The tolerance ring  200  and/or sidewall  202  may have an inner surface  230 , and an outer surface  232 . The sidewall  202  also may have a plurality of projections  208  ( 208   a ,  208   b ) that extend radially inward from its inner surface  130 . The projections  208  ( 208   a ,  208   b ) may circumferentially abut one other as shown, or be circumferentially spaced-apart as in the embodiment of  FIG. 3A . The projections  208  ( 208   a ,  208   b ) may be of similar shape, parameter (e.g., radial height of the projections, stiffness of the projections), or orientation as the projections  108  ( 108   a ,  108   b ) described above in  FIGS. 3A-3C . 
     In operation, the tolerance ring  100  may be located between two components in an assembly. For example, it may be located in the annular space between an inner component (for example, a shaft) and a bore in an outer component (for example, a housing). The projections  108  may be compressed between the inner and outer components. Each projection  108  may act as a spring and deforms to fit the components together with zero clearance therebetween. In other words, the inner component contacts the inner surfaces  130  of the tolerance ring  100  and the outer component contacts the outer surfaces  132  of the tolerance ring  100 . 
       FIG. 5A  depicts an axial sectional view through an exemplary assembly  300  including an embodiment of a tolerance ring  200 . The assembly  300  incorporates, for example, the tolerance ring  200  shown in  FIG. 3A . The assembly  300  may include a housing  302  or outer component down a central axis  3000 . The housing  302  may have an axial bore  304  formed therein, which receives a shaft  306  or inner component. An annular gap exists between the outer surface  308  of shaft  306  and the inner surface  310  of bore  304 . The size of this annular gap may be variable because the diameter of the shaft  306  and bore  304  may vary within manufacturing tolerances. To prevent vibration of the shaft  306  within the bore  304 , the annular gap is filled by tolerance ring  200  to form a zero-clearance fit between the components. In use, the circumferential projections  208  of the tolerance ring  200  may be radially compressed in the annular gap between the shaft  306  and housing  302 , such that the projections  208  contact the inner component  306 . Tolerance rings may be used to transfer torque or as torque limiters in such applications. 
       FIG. 5B  depicts an axial sectional view through an exemplary assembly  400  including another embodiment of a tolerance ring  100 . The assembly  300  incorporates, for example, the tolerance ring  100  shown in  FIG. 3A . The assembly  400  may include a housing  302  or outer component down a central axis  3000 . The housing  302  may have an axial bore  304  formed therein, which receives a shaft  306  or inner component. An annular gap exists between the outer surface  308  of shaft  306  and the inner surface  310  of bore  304 . The size of this annular gap may be variable because the diameter of the shaft  306  and bore  304  may vary within manufacturing tolerances. To prevent vibration of the shaft  306  within the bore  304 , the annular gap is filled by tolerance ring  100  to form a zero-clearance fit between the components. In use, the circumferential projections  108  of the tolerance ring  100  may be radially compressed in the annular gap between the shaft  306  and inside of the bore  304  of the housing  302 , such that the projections  108  contact the outer component  302 . 
     In a number of embodiments, as shown in  FIGS. 3A and 4-5B , the tolerance ring  100 ,  200  may have a length L TR  as measured between the first axial end  120 ,  220 , and the second axial end  122 ,  22  of the tolerance ring  100 ,  200 . It will be appreciated that the length L TR  may be substantially similar to the length of the material or composite material  1000 ,  1001 ,  1002 ,  1003  as shown in  FIGS. 2A-2D . According to certain embodiment, the length L TR  of the tolerance ring  100 ,  200  may be at least about 1 mm, such as, at least about 10 mm or at least about 30 mm or at least about 50 mm or at least about 100 mm or even at least about 500 mm. According to still other embodiments, the length L TR  of the tolerance ring  100 ,  200  may be not greater than about 1000 mm, such as, not greater than about 500 mm or even not greater than about 250 mm. It will be appreciated that the length L TR  of the tolerance ring  100 ,  200  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the length L TR  of the tolerance ring  100 ,  200  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that length L TR  of the tolerance ring  100 ,  200  may vary along its circumference. 
     In a number of embodiments, as shown best in  FIGS. 3B and 5B , the tolerance ring  100 ,  200  may have a particular inner radius IR TR . For purposes of embodiments described herein, the inner radius IR TR  of the tolerance ring  100 ,  200  is the distance from the central axis  3000  to the inner surface  130 ,  230 . According to certain embodiment, the inner radius IR TR  of the tolerance ring  100 ,  200  may be at least about 10 mm or at least about 20 mm or at least about 30 mm or at least about 50 mm or even at least about 100 mm. According to still other embodiments, the inner radius IR TR  of the tolerance ring  100 ,  200  may be not greater than about 500 mm, such as, not greater than about 250 mm or even not greater than about 100 mm. It will be appreciated that the inner radius IR TR  of the tolerance ring  100 ,  200  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the inner radius IR TR  of the tolerance ring  100 ,  200  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that the inner radius IR TR  of the tolerance ring  100 ,  200  may vary along its circumference and may vary across a plurality of tolerance rings. 
     In a number of embodiments, as shown best in  FIGS. 3B and 5B , the tolerance ring  100 ,  200  may have a particular outer radius OR TR . For purposes of embodiments described herein, the outer radius OR TR  of the tolerance ring  100 ,  200  is the distance from the central axis  3000  to the outer surface  132 ,  232 . According to certain embodiment, the outer radius OR TR  of the tolerance ring  100 ,  200  may be at least about 10 mm or at least about 20 mm or at least about 30 mm or at least about 50 mm or even at least about 100 mm. According to still other embodiments, the outer radius OR TR  of the tolerance ring  100 ,  200  may be not greater than about 500 mm, such as, not greater than about 250 mm or even not greater than about 100 mm. It will be appreciated that the outer radius OR TR  of the tolerance ring  100 ,  200  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the outer radius OR TR  of the tolerance ring  100 ,  200  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that the outer radius OR TR  of the tolerance ring  100 ,  200  may vary along its circumference and may vary across a plurality of tolerance rings. 
     In a number of embodiments, as shown best in  FIGS. 2A-2D and 5A , the tolerance ring  100 ,  200  may have a particular thickness T TR . For purposes of embodiments described herein, the thickness T TR  of the tolerance ring  100 ,  200  is the distance from the inner surface  130 ,  230  to the outer surface  132 ,  232 . It will be appreciated that thickness T TR  of the tolerance ring  100 ,  200  may be substantially similar or the same thickness as the material or composite material  1000 ,  1001 ,  1002 ,  1003  as shown in  FIGS. 2A-2D . According to certain embodiment, the thickness T TR  of the tolerance ring  100 ,  200  may be at least about 0.1 mm or at least about 0.2 mm or at least about 0.3 mm or at least about 0.4 mm or even at least about 0.5 mm. According to still other embodiments, the T TR  of the tolerance ring  100 ,  200  may be not greater than about 1 mm, such as, not greater than about 0.9 mm or even not greater than about 0.8 mm. It will be appreciated that the thickness T TR  of the tolerance ring  100 ,  200  may be within a range between any of the minimum and maximum values noted above. It will be further appreciated that the thickness T TR  of the tolerance ring  100 ,  200  may be any value between any of the minimum and maximum values noted above. It can also be appreciated that the thickness T TR  of the tolerance ring  100 ,  200  may vary along its circumference. It can also be appreciated that thickness T TR  of the tolerance ring  100 ,  200  may vary along its circumference and may vary across a plurality of tolerance rings. 
       FIG. 6  depicts an end view through an exemplary assembly  500  including another embodiment of a tolerance ring  100 . The assembly  500  incorporates, for example, the tolerance ring  100  shown in  FIG. 3A . The assembly  500  may include a housing  302  or outer component. The housing  302  may have an axial bore  304  formed therein, which receives a shaft  306  or inner component. An annular gap exists between the outer surface  308  of shaft  306  and the inner surface  310  of bore  304 . The size of this annular gap may be variable because the diameter of the shaft  306  and bore  304  may vary within manufacturing tolerances. To prevent vibration of the shaft  306  within the bore  304 , the annular gap is filled by tolerance ring  100  to form a zero-clearance fit between the components. In use, the circumferential projections  108  of the tolerance ring  100  may be radially compressed in the annular gap between the shaft  306  and inside of the bore  304  of the housing  302 , such that the projections  108  contact the outer component  302 . In this embodiment, at least one of the inner component  306  or the outer component  302  may include a groove  303  adapted to house at least one of the projections  108  to prevent circumferential movement between the tolerance ring projection  108  and the groove  303 . In another embodiment, the at least one of the inner component  306  or the outer component  302  may include a groove adapted to house the tolerance ring  100  itself to prevent axial movement between the tolerance ring  100  and the inner component  306  or the outer component  302 . For example, as shown in  FIG. 6 , the groove  303  may be located on the outer component  302  and house a radially extending projection of the second type projecting outwardly  108   b . As a result, the tolerance ring  100  may be constrained from moving in the axial or circumferential direction along or about the central axis  3000  due to a lock between the projection  108   b  and the groove  303  in the outer component  302 . 
     In at least one embodiment, the assembly  300 ,  400 ,  500  may include a lubricant. In at least one embodiment, the lubricant may include a grease including at least one of lithium soap, lithium disulfide, graphite, mineral or vegetable oil, silicone grease, fluoroether-based grease, apiezon, food-grade grease, petrochemical grease, or may be a different type. In at least one embodiment, the lubricant may include an oil including at least one of a Group I-Group III+oil, paraffinic oil, naphthenic oil, aromatic oil, biolubricant, castor oil, canola oil, palm oil, sunflower seed oil, rapeseed oil, tall oil, lanolin, synthetic oil, polyalpha-olefin, synthetic ester, polyalkylene glycol, phosphate ester, alkylated naphthalene, silicate ester, ionic fluid, multiply alkylated cyclopentane, petrochemical based oil, or may be a different type. In at least one embodiment, the lubricant may include a solid based lubricant including at least one of lithium soap, graphite, boron nitride, molybdenum disulfide, tungsten disulfide, polytetrafluoroethylene, a metal, a metal alloy, or may be a different type. In the case of using a lubricant, it is desirably disposed at least along the desired slip interface (described below). 
     In normal operation a rotational torque is applied to one of the inner and outer components, and that torque is transferred by the interference fit of the tolerance ring to the other of the inner and outer components. However, should one of the components be rotationally bound up, the tolerance ring functions to allow slippage between the inner and outer components. According to embodiments herein, that slippage happens at a desired slip interface, generally the surface opposite the projections. For example, in some embodiments shown having outwardly projecting projections, the slip interface occurs along the radially inside surface of the tolerance ring, at the tolerance ring/inner component interface. This may be due to using a first type of radially extending projection and a second type of radially extending projection with different properties from each other based on differences in radial height, circumferential width, shoulder length, slope, or stiffness, as described above. In order to ensure slippage at the desired interface, opposite the waves/projections, the breakaway torque, τ, at the two interfaces (radially opposite surfaces of the tolerance ring) are different. The breakaway torque, τ, is defined below. Here, the breakaway torque, τ, at the desired slip interface is lower than the breakaway torque, τ, at the non-slip interface. 
     By non-limiting example, the second type of projections  108   b  may include sharper profiles that may engage more aggressively into the inner or outer component that the projections contact. The second type of projections  108   b  may have differences in their parameters (e.g. radial height, circumferential width, shoulder length, slope, or stiffness) from the first type of projections  108   a  that may cause the sharper profile and provide different behaviors and properties of each type of projections. As a result, according to certain embodiments, the first type of projection provides a desired tolerance compensation to accommodate manufacturing tolerance between the inner and outer components. In addition, the second type provides enhanced ‘bite’ or ‘grip’ between the tolerance ring and the contacting inner/outer member, which in turn enhances the breakaway torque at that interface. The number, placement, and parameters (e.g., radial height, circumferential width, shoulder length, slope, or stiffness) of the second type of projections  108   b  versus the first type of projections  108   a  are chosen to give the projections different properties and/or behaviors to achieve desired slip performance with a robust torque performance whilst constraining the slip to the desired surface of the inner or outer component. 
     According to embodiments, the tolerance ring may have a first break-away torque, τ 1 , defined as the breakaway torque between the tolerance ring projections and the inner or outer component that the projections contact, and a second break-away torque, τ 2 , defined as the breakaway torque between the unformed region and the other of the inner and outer components. In a number of embodiments, 1.1 τ 2 ≤τ 1 , such as 1.2 τ 2 ≤τ 1 , such as 1.5 τ 2 ≤τ 1 , such as 2 τ 2 ≤τ 1 , or even 5 τ 2 ≤τ 1 . As previously mentioned, the first type of projections may be adapted to provide tolerance compensation between the inner and outer components, and a second type of projections may be adapted to engage the inner component  306  or the outer component  302  to increase circumferential break-away torque, τ2 at that interface. 
     Measurement of torque values as described herein is done with a torque test apparatus model Helixa-i provided by Mecmesin Ltd. The tolerance ring is disposed between inner and outer components, and securely fastened to the inner component to measure breakaway torque at the radially outer interface, then in a separate test, is securely fastened to the outer component in order to measure breakaway torque at the radially inner interface. Fastening may be done using a glue such as Super Glue that is designed to affix metal components to each other. The apparatus is run at room temperature (about 21° C.)+360°, −360° at 30 rpm for 50 cycles to apply increased torque between the inner and outer components and the measured peak torque is recorded, which generally correlates to the torque value as slippage initiates. The test is run on tolerance rings having no low friction coating but with grease provided along the slip interface being evaluated. Consequently, in an embodiment having a low friction layer, the test is done with the low friction layer removed in order to ensure the measured breakaway torque values are not dependent on such a low friction layer. A sample resulting graph of the torque (N·m) as a function of the time (s) is shown as  FIG. 7 . As shown, the circled area  702  is where the break torque occurs. 
     Examples 
     Two tolerance rings were tested. The first tolerance ring (Ring A) is a control ring which had only projections of the first type of projection facing radially outwards. A drawing of Ring A  800  in several views in a free state condition or a mounted condition (around an inner component  306 ) is shown in  FIG. 8 . Ring A has 14 of the first type of projections equally spaced around the circumference with allowable burr specification of 0.2 max. When assembled between an 11.859 mm diameter inner component and a 12.692 mm outer component, an assembly force of 18 to 32 kg was felt. The end wave height was about 0.42 mm minimum. Ring A has a 12.5 mm diameter, a 3 mm length, and a 0.2+/−0.013 mm thickness. Ring A has a material hardness of about 400 to about 450 VPN. Ring A is made of stainless steel. The second tolerance ring (Ring B) is an experimental ring according to embodiments herein which had projections of the first type of projection and projections of the second type of projection both facing radially outwards. A drawing of Ring B  900  in several views in a free state condition or a mounted condition (around an inner component  306 ) is shown in  FIG. 9 . Ring B has 10 of the first type of projections and 4 of the second type of projections equally spaced around the circumference as shown with allowable burr specification of 0.2 max. When assembled between an 11.82 mm diameter inner component and a 12.692 mm outer component, an assembly force of 18 to 32 kg was felt. The end wave height was about 0.42 mm minimum. Ring B has a 12.5 mm diameter, a 3 mm length, and a 0.2+/−0.013 mm thickness. Ring B has a material hardness of about 400 to about 450 VPN. Ring B is made of stainless steel. The tolerance rings were designed such that slip was desired to occur against the shaft instead of the housing. Rings A and B were both tested for slip torque in two conditions: 1) glued to a shaft or inner component to ensure a slip on a slip surface on the housing or outer component; or 2) glued to a housing or outer component to ensure a slip on a slip surface on the shaft or inner component. The inner component and outer component for these tests were both brass C3604 and a lubricant was applied between the tolerance rings and only the slip surface of either the inner component or the outer component. The results of these tests are shown in Table 1 below: 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Condition 1: Break 
                 Condition 2: Break 
               
               
                   
                 Torque against 
                 Torque against 
               
               
                   
                 Housing Slip Surface 
                 Shaft Slip Surface 
               
               
                   
                 (N · m) 
                 (N · m) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Ring A 
                 2 
                 3 
               
               
                   
                 Ring B 
                 4 
                 3 
               
               
                   
                   
               
            
           
         
       
     
     As shown, the tendency of the system is to slip against the housing, as the torque required to do so was lower than it was on the shaft. Further as shown, Ring B with two types of projections had approximately double the torque at which slip occurs in the housing while having minor effect on the torque for slip on the shaft. Therefore, it may be concluded that the torque to slip on the shaft is lower than the torque to slip in the housing, so the slip will be on the shaft due to inclusion of the second type of projection. 
     Applications for such embodiments include, for example, assemblies related to rotational devices such as an electric motor (such as a windshield wiper motor), or axial sliding applications (such as a steering column adjustment mechanism). Embodiments disclosed herein have applications found in robotics, mechatronics, automotive components, or other uses. Use of the tolerance ring or assemblies may provide increased benefits in several applications. According to embodiments herein, the tolerance ring may provide desired slip only at a desired interface. This feature can protect the components of the assembly  300 ,  400 ,  500  from overload by slipping at a predetermined level of torque over multiple operation cycles at a desired surface (in the axial or circumferential direction) without significant change to the torque value at which the slip occurs. Additionally, by configuring the tolerance ring to slip at only one of the two possibly slip interfaces, the tolerance ring can be maintained in position within the assembly, such as by preventing it from migrating axially along the housing or shaft in the case of a rotational assembly. As a result, tolerance rings  100 ,  200  according to embodiments herein may improve torque or slip performance while maintaining appropriate tolerance compensation and position, resulting in increased lifetime and improved effectiveness and performance of the assembly, the tolerance ring, and other neighboring components. 
     Many different aspects and embodiments are possible. Some of those aspects and embodiments are described below. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention. Embodiments may be in accordance with any one or more of the embodiments as listed below. 
     Embodiment 1 
     A tolerance ring comprising: a sidewall comprising a plurality of radially extending projections on a first radial surface and an unformed region on a second radial surface opposite the first radial surface, wherein the tolerance ring provides a first break-away torque, τ1, defined as the breakaway torque between the tolerance ring projections and an inner component or an outer component, wherein the tolerance ring provides a second break-away torque, τ2, defined as the breakaway torque between the unformed region and the other of the inner component or the outer component, and wherein 1.1 τ2≤τ1. 
     Embodiment 2 
     An assembly comprising: an inner component; an outer component; and a tolerance ring located between the inner and outer components to provide an interference fit there between, the tolerance ring comprising a sidewall comprising a plurality of radially extending projections on a first radial surface and an unformed region on a second radial surface opposite the first radial surface, wherein the tolerance ring provides a first break-away torque, τ1, defined as the breakaway torque between the tolerance ring projections and an inner component or an outer component, wherein the tolerance ring provides a second break-away torque, τ2, defined as the breakaway torque between the unformed region and the other of the inner component or the outer component, and wherein 1.1 τ2≤τ1. 
     Embodiment 3 
     The tolerance ring or assembly of any of the preceding embodiments, wherein 1.2 τ2≤τ1, 1.5 τ2≤τ1, 2 τ2≤τ1, or 5 τ2≤τ1. 
     Embodiment 4 
     The tolerance ring or assembly of any of the preceding embodiments, wherein the tolerance ring projections comprise first type of projections adapted to provide tolerance compensation between the inner component and the outer component, and a second type of projections adapted to engage the inner component or the outer component to increase circumferential break-away torque, τ, between the tolerance ring and the inner component or the outer component. 
     Embodiment 5 
     The tolerance ring or assembly of any of the preceding embodiments, wherein each of the projections includes a circumferential width and a radial height, and a circumferential ridge extending in the radial direction, the ridge rising to and falling from a peak within the circumferential width and being axially bound by a pair of shoulders. 
     Embodiment 6 
     The tolerance ring or assembly of embodiment 5, wherein the first type of projections comprises a different radial height versus the second type of projections. 
     Embodiment 7 
     The tolerance ring or assembly of embodiment 5, wherein the first type of projections comprises a different circumferential width versus the second type of projections. 
     Embodiment 8 
     The tolerance ring or assembly of embodiment 5, wherein the first type of projections comprises a different shoulder length versus the second type of projections. 
     Embodiment 9 
     The tolerance ring of embodiment 5, wherein the first type of projections comprises a different slope of the circumferential ridge versus the second type of projections. 
     Embodiment 10 
     The tolerance ring of embodiment 4, wherein the first type of projections comprises a different stiffness versus the second type of projections. 
     Embodiment 11 
     The tolerance ring or assembly of any of the preceding embodiments, wherein the plurality of projections extend radially inward and contact the inner component. 
     Embodiment 12 
     The tolerance ring or assembly of any of the preceding embodiments, wherein the plurality of projections extend radially outward and contact the outer component. 
     Embodiment 13 
     The tolerance ring or assembly of any of the preceding embodiments, wherein at least one of the inner component or the outer component comprises a groove adapted to house at least one of the projections to prevent circumferential movement between the tolerance ring projection and the groove. 
     Embodiment 14 
     The tolerance ring or assembly of any of the preceding embodiments, wherein the tolerance ring has an axial gap. 
     Embodiment 15 
     The tolerance ring or assembly of any of the preceding embodiments, wherein the sidewall comprises a metal. 
     Embodiment 16 
     The tolerance ring or assembly of embodiment 15, wherein the metal comprises a carbon steel or stainless steel. 
     Embodiment 17 
     The tolerance ring or assembly of embodiment 15, wherein the first radial surface and the second radial surface comprise a metal exterior surface. 
     Embodiment 18 
     The tolerance ring or assembly any of the preceding embodiments, wherein the tolerance ring has an inner radius within the range of AA-BB mm. 
     Embodiment 19 
     The tolerance ring or assembly of any of the preceding embodiments, wherein the tolerance ring has an outer radius within the range of CC mm-DD mm. 
     Embodiment 20 
     The tolerance ring or assembly of any of the preceding embodiments, wherein the tolerance ring has a length within the range of FF to GG mm. 
     Embodiment 21 
     The tolerance ring or assembly of any of the preceding embodiments, wherein the tolerance ring comprises a lubricant. 
     Note that not all of the features described above are required, that a region of a specific feature may not be required, and that one or more features may be provided in addition to those described. Still further, the order in which features are described is not necessarily the order in which the features are installed. 
     Certain features are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombinations. 
     Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments, however, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims. 
     The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of assembly and systems that use the structures or methods described herein. Separate embodiments may also be provided in combination in a single embodiment, and conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, reference to values stated in ranges includes each and every value within that range. Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or any change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.