## 4. Constructional and Functional Aspects of Chains
### Requirements and Dimensioning
Figure 6: Geometric characteristics of a metal link in a technical chain. The primary material used in the production of link chains is high-strength steel, which ensures adequate resistance to both dynamic and static loads. Standards developed by international standardization bodies define numerous minimum requirements for such chains. An example of a high-strength chain--with a nominal load capacity of 850 kg and round links--should be designed and manufactured in accordance with ISO 610:2015, High-tensile steel chains (round link) for chain conveyors and coal plows [106]. This standard also refers to other related norms, including ISO 643:1983, Steels--Micrographic determination of the ferritin or austenitic grain size [107], and ISO 7500:1986, Metallic materials--Verification of static uniaxial testing machines--Part 1: Tensile testing machines [108]. When designing technical chains, several material, dimensional, and performance-related requirements must be considered to ensure proper functionality and safety. The following section outlines key provisions addressed by ISO 610. The ISO 610 standard specifies requirements for a series of high-quality, specialized steel chains with calibrated, high-tensile, electrically welded round links. These chains are intended for use in mining equipment such as chain conveyors, chain-belt conveyors, gate and bridge conveyors, bucket elevators, coal plows, coal cutters, mechanical loaders, and other similar machinery, including systems used in underground mining operations. Chains covered by this standard are not intended for lifting applications, such as cranes or slings. The standard defines the following terms:  
* Chain size, defined as the nominal diameter of the wire or steel rod used to produce the chain. * Breaking force--the maximum tensile force a finished chain sample can withstand before failure. * Proof force--a specified force that a finished chain sample must withstand without exceeding the defined elongation limit. \begin{table}
\begin{tabular}{c c l} \hline \hline
**Standard** & **Number** & **Title** \\ \hline DIN & 763 & Tested, non-calibrated, long-link round steel chains [88] \\ DIN & 764 & Calibrated and tested round steel link chains for continuous conveyors [89] \\ DIN & 766 & Calibrated and tested grade 3 round steel link chains [90] \\ DIN & 5692 & Round steel link chains—Forged steel components—Chain shortener, grade 8 [91] \\ DIN & 8197 & Steel link chains—Reference profiles of hobs for sprockets for roller chains [92] \\ DIN & 5684 & Calibrated and tested round steel link chains for lifting purposes [93] \\ DIN & 5687-1 & Round steel link chains—Part 1: Grade 5, medium tolerance, tested [94] \\ DIN & 17115 & Steels for welded round link chains and chain components—Technical delivery conditions [95] \\ DIN & 22252 & Round link chains for use in continuous conveyors and winning in mining [96] \\ DIN & 22255 & Flat link chains for use in continuous conveyors in mining [97] \\ DIN & 32891 & Tested non-calibrated round steel link chains—Grade 2 [98] \\ DIN EN & 818 & Short link chain for lifting purposes [99] \\ ASME & B29.22-2001 & Drop Forged Rivetless Chains, Sprocket Teeth Drive Chain/Drive Dogs [100] \\ ASTM & Volume 01.05 & Steel–Bars, Forgings, Bearing, Chain, Tool [101] \\ ASTM & A0466-2007 & Standard Specification for Weldless Chain [102] \\ ASTM & A0413-2021 & Standard Specification for Carbon Steel Chain [103] \\ ASTM & A0391-2021 & Standard Specification for Grade 80 Alloy Steel Chain [104] \\ ASTM & A0973-2021 & Standard Specification for Grade 100 Alloy Steel Chain [105] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._* Acceptance force -- a specified force that must be applied to the entire chain after processing, without causing permanent deformation or damage; this force may be reapplied at the discretion of the purchaser or inspector. * Percentage elongation--the measured elongation expressed as a percentage of the gauge length. * Processing--any post-welding operation such as heat treatment, calibration, or surface finishing.