Schedule of Accreditation
issued byUnited Kingdom Accreditation Service
2 Pine Trees, Chertsey Lane, Staines-upon-Thames, TW18 3HR, UK

Vision Engineering Limited
Issue No: 001

7706
Accredited toISO/IEC 17025:2017

Issue date: 05 May 2020

Freeman Building

Contact: John Marshall

Galileo Drive

Tel: +44 (0) 1483 248300

Send

E-Mail: generalinfo@visioneng.com

WokingWebsite: www.visioneng.com

SurreyGU23 7ER
United Kingdom

Calibration performed at the above address only

DETAIL OF ACCREDITATION

Measured Quantity
Instrument or Gauge

Calibration andMeasurement Capability(CMC) Expressed as an
Expanded Uncertainty(k = 2)

Range

Remarks

MEASURING INSTRUMENTS
AND MACHINES
X-Y Stages

From 150 mm x 100 mm upto
400 mm x 300 mm

Linear:
1.5 + (1.1 x length in m) µm

Accreditation is limited tostages manufactured by Vision
Engineering Ltd.

Squareness: 0.0060 °END

Assessment Manager: JS4

Page 1 of 2

S c he dul e of Ac c re di ta ti on
issued byUnited Kingdom Accreditation Service
2 Pine Trees, Chertsey Lane, Staines -upon-Thames, TW18 3HR, UK

Vision Engineering Limited
Issue No: 0017706
Accredited to
ISO/IEC 17025:2017

Issue date: 05 May 2020Calibration performed at main address only

Appendix - Calibration and Measurement Capabilities
Introduction
The definitive statement of the accreditation status of a calibration laboratory is the Accreditation Certificate and the associated Schedule ofAccreditation. This Schedule of Accreditation is a critical document, as it defines the measurement capabilities, ranges and boundaries of thecalibration activities for which the organisation holds accreditation.
Calibration and Measurement Capabilities (CMCs)
The capabilities provided by accredited calibration laboratories are described by the Calibration and Measurement Capability (CMC), which
expresses the lowest uncertainty of measurement that can be achieved during a calibration. If a particular device under calibration itself
contributes significantly to the uncertainty (for example, if it has limited resolution or exhibits significant non-repeatability) then the uncertainty
quoted on a calibration certificate will be increased to account for such factors. The CIPM-ILAC definition of the CMC is as follows:
A CMC is a calibration and measurement capability available to customers under normal conditions:(a) as published in the BIPM key comparison database (KCDB) of the CIPM MRA; or(b) as described in the laboratory’s scope of accreditation granted by a signatory to the ILAC Arrangement.
The CMC is normally used to describe the uncertainty that appears in an accredited calibration laboratory's schedule of accreditation and is theuncertainty for which the laboratory has been accredited using the procedure that was the subject of assessment. The CMC is calculated
according to the procedures given in M3003 and is normally stated as an expanded uncertainty at a coverage probability of 95 %, whichusually requires the use of a coverage factor of k = 2. An accredited laboratory is not permitted to quote an uncertainty that is smaller than thepublished CMC in certificates issued under its accreditation.
The CMC may be described using various methods in the Schedule of Accreditation:
As a single value that is valid throughout the range.
As an explicit function of the measurand or of a parameter (see below).
As a range of values. The range is stated such that the customer can make a reasonable estimate of the likely uncertainty at any point within
the range.
As a matrix or table where the CMCs depend on the values of the measurand and a further quantity.
In graphical form, providing there is sufficient resolution on each axis to obtain at least two significant figures for the CMC.
Expression of CMCs - symbols and units
In general, only units of the SI and those units recognised for use with the SI are used to express the values of quantities and of the associated
CMCs. Nevertheless, other commonly used units may be used where considered appropriate for the intended audience. For example, the term“ppm” (part per million) is frequently used by manufacturers of test and measurement equipment to specify the performance of their products.
Terms like this may be used in Schedules of Accreditation where they are in common use and understood by the users of such equipment,
providing their use does not introduce any ambiguity in the capability that is being described.
When the CMC is expressed as an explicit function of the measurand or of a parameter, this often comprises a relative term (e.g., percentage)
and an absolute term, i.e. one expressed in the same units as those of the measurand. This form of expression is used to describe thecapability that can be achieved over a range of values. Some examples are shown below. It should be noted that these expressions are notmathematical formulae but are instead written in a commonly used shorthand for expressing uncertainties - therefore, for purposes of clarity,
an indication of how they are to be interpreted is also provided below.
DC voltage, 100 mV to 1 V: 0.0025 % + 5.0 μV
Over the range 100 mV to 1 V, the CMC is 0.0025 %∙V + 5.0 μV, where V is the measured voltage.
Hydraulic pressure, 0.5 MPa to 140 MPa: 0.0036 % + 0.12 ppm/MPa + 4.0 Pa
Over the range 0.5 MPa to 140 MPa, the CMC is 0.0036 %∙p + (0.12∙10-6∙p∙10-6) + 4.0 Pa, where p is the measured pressure in Pa.
It should be noted that the percentage symbol (%) simply represents the number 0.01. In cases where the CMC is stated only as a percentage,
this is to be interpreted as meaning percentage of the measured value or indication.
Thus, for example, a CMC of 1.5 % means 1.5 ∙ 0.01 ∙ i, where i is the instrument indication.

Assessment Manager: JS4

Page 2 of 2