First Principles of Inspection

What is Quality?

Quality is a process used within the business to determine whether or not a component meets the demands of the drawing and the customer requirements.

The requirements are:

• Dimensional, ensuring that all dimensions are within stated tolerances
• Visual, certifying the overall condition meets requirements
• Material, the correct material is used and the condition is good
• Further subcontract processes, which includes plating, powder coating, and deburring services

Quality Control  

Quality Control is the final step at the end of the manufacturing process which ensures all components meet the required standard before they are sent to customers.

Quality Assurance

Quality Assurance starts at the beginning of the manufacturing process, forming the new product introduction (NPI) where all risks are predefined to eliminate issues.

The purpose of this process is to ensure no non-conforming parts are being manufactured and that the product is fit for use. However, this may not always be the case, therefore a Plan To Do Check (PDCA) cycle can be implemented to improve the process.

Direct measurement:

Direct measurement is a type of measurement which is conducted by physically measuring the component with the use of various measurement equipment. This type of measurement produces a value of the dimension.

Comparative measurements:

This is a type of measurement which compares a dimension against a known standard and only shows whether the dimension is within tolerance and no what the actual size is.

Direct measurement equipment:

• Micrometre
• Height gauge
• Drop clock
• Bore micrometre

Comparative measurement equipment:

• Plug gauges
• Screw plug gauges
• Ring gauges
• Ring threads gauges
• Visual surface roughness comparators

How gauges are controlled

Technoturn has a range of gauges that are used regularly for in-process checks by machinists, as well as first-off inspections and batch inspections. When the gauges are needed, they are booked in and out of the data track MRP system. This system has one specific module which is used to control gauge issuing and gauge calibration, ensuring that all gauge locations are known and are all calibrated.

This system controls calibration requirements and call-offs to ensure that all components are measured against an accurate and precise attribute. Another feature of the system is the ability to notify users when the measurement equipment is near the calibration date or is out of calibration.

• Once a job is planned and the machine of choice is selected, the operator would set the machine to produce a dimensionally and visually correct component. They would complete this with the aid of the in-process inspection checklist, which holds the information on the predefined measurement equipment used on specific dimensions.

• When the component is within tolerance and meets the correct standards, the setter submits the component to the quality department for them to inspect.
• Once the inspector receives the component, they would check all relevant documentation related to the job. This includes material certification, revision of drawing, and any known non-conformances/previous non-conformances.
• When all paperwork meets the requirements, the first-off inspection can begin. This consists of a thorough visual inspection to ensure there are no burrs, no poor surface finish, no general damage, and it is the correct orientation. This is completed with the use of a Mantis elite microscope, which is capable of 15x magnification.

• The next step is to measure the dimensions of the components against the setter’s values to ensure the part is measured correctly and accurately. The values are retrieved by the inspector or logged into the inspection checklist with the same instruments as the setter.
• When measuring the dimension, we would aim for the dimension to be at the nominal value. If these are not complying to the stated specifications, the inspector would log the dimensions and how much they were out of tolerance, report the issue to the setter to rectify, understand how they completed the measurement and why it was wrong. The operation would resolve the issue, and it is then re-submitted for another first-off inspection process to be completed.
• For the component to be passed off, all the requirements stated must be correct such as material, revision, dimensions, and visual requirements.
• Once the inspector is happy to pass off the component, they would keep the sample for future reference for a predefined period. Only then the component is allowed to go into full production.

Once the first off inspection is complete, production begins and the machinist receives an in-process inspection sheet that states a given timescale of when to perform checks. Depending on the job, some features may require 100% verification of specific dimensions that are stated on the drawings and checklist.

Twice a day, each machine will submit a component which is checked by the operator and an inspector checks against these measurements to ensure that they are measured correctly and are being manufactured to the correct requirements. If any issues are found, they can be eliminated as soon as possible.

At the end of all machining, process components are submitted for final inspection before dispatch. The inspection process can deviate depending on the customer requirements. If any non-conforming parts are found, production must stop until the issue is fixed and the entire batch is checked to ensure all non-conformance’s are found.