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Measuring & Inspection Explained

Mark Nieschmidt

Senior Technical Support

 

Measuring tools are very common in the engineering and manufacturing industry. Whether you're using precision measuring tools or standard measuring instruments, it's important to use the correct tools to gain accurate results whilst machining.

Why use measuring tools?

Measuring tools are used to ensure that workpieces have been machined correctly to the required standard and tolerance. Precision measuring tools are usually used on CNC machined parts because these are measurements that are not visible to the naked eye, with tolerances often being a matter of a single micron (0.001mm).

What measuring tools are used at each stage of the production process?

Measuring instruments are used in the pre-machining phase where machinists use them to gauge which raw materials to use for a particular job. During the actual machining process, measuring tools are used to inspect the workpiece and make sure it is being machined as intended. The final inspection phase is then used in order to verify that the finished workpiece has been delivered as per the original drawing and/or specification. It is common practice to measure all components and features during a production run to ensure manufacturing consistency. 

What types of measuring tools are there?

There are different types of measuring tools that can measure, gauge and check a workpiece. Workpieces can be measured (gauged or checked) for various things including external widths or heights, internal bore diameters and thread quality. Popular measuring tools include Digital Calipers, Vernier Calipers, Indicators, Height Gauges, Depth Gauges, Micrometers, Gauge Blocks and Thread Gauges.

There are also measuring tools that can be used to ensure the correct setup for a job on the machine with ultimate precision and accuracy such as edge finders, centering indicators, 3D sensors and zero setters.

What is the difference between a digital, dial and vernier measuring tool?

Digital measuring tools have an LCD (liquid crystal display) to provide easy-to-read, high accuracy measurements. Vernier or analogue measuring tools require a manual reading, whereas a dial tool will feature a circular dial in the centre which will provide higher accuracy than vernier tools due to easier measurement readings.

 

What is calibration and why should you calibrate your measuring tools?

Calibration is checking a measuring instrument to see if it is accuate within dimensional specification. UKAS (United Kingdom Accreditation Service) are the nationally appointed organisation to assess certification, testing, inspection and calibration against agreed standards. UKAS calibrated products are supplied with an official testing certificate that that confirms the measuring tool has been manufactured and operates at the high standards required. By calibrating your measuring tools, you can ensure that the measuring tools will measure within the desired range for your application. 

How often should you re-calibrate your measuring tools?

Over time, measuring tools can degrade and start to show inaccurate readings, this is mainly due to general wear and tear of the product. Therefore, re-calibration is required in order to maintain high levels of accuracy. Most tools come with a recommend calibration interval to ensure you are checking them regularly, but this can also be dependent on the usage. More frequent calibration will be required for high usage measuring tools.

What are IP ratings and why are they important?

Many digital tools are available with an IP rating (ingress protection). This is the level of protection a measuring tool has against liquids or dust. The most common IP ratings in precision measuring tools are:

IP54 – Offers protection against a certain amount of dust levels but is not fully dust proof. It is also protected against splashing water or coolant (but not submerged in it).

IP65 – Gives protection against low pressure water jets from any angle. Fully dust proof.

IP67 - Fully dust proof and protected from full immersion in water or coolant for a maximum of 30 minutes.

Shop Cutwel's Measuring & Inspection ranges...

Calipers

Digital calipers from Insize, Mitutoyo, Sylvac, Mahr & Moore & Wright & Mahr either with or without data output.

Micrometers

Digital, dial & analogue micrometers from Insize, Mitutoyo & Mahr.

Bore Gauges

Precision Bore Gauges, Internal 3 Point Bore Micrometers & 2 Point Inside Micrometers from Insize, Bowers & Mitutoyo.