If you’re buying precision machined components, you don’t expect problems with assembly or function. Leaks, excessively high or low friction, and fit issues will all be expensive to deal with and could even result in warranty claims. The way to avoid these is by going to a precision machine shop that has the resources to deliver “perfect” every time. Here’s how Impro provides that level of service.

Organizing for Perfection

Meeting and exceeding customer requirements is a team effort. While the whole organization is involved, five especially important elements are:

• Quality management
• Machine maintenance
• Tool presetting
• Material quality
• Inspection and test

Quality Management

Inspection and test are part of quality control, but they don’t make bad parts better. All they can do is verify conformance to specifications. That’s important, but what matters more is having systems in place to ensure customer expectations are understood, and the business is capable of meeting them.

This is done by operating a Quality Management System (QMS) that meets the criteria set out in standards like ISO 9001 and IATF 16949. These require Standard Operating Procedures (SOPs) that eliminate variation in the way jobs are done, promote a proactive stance towards satisfying customer requirements, and push for continuous improvement.

Machine Maintenance

Achieving high precision and satisfactory surface finishes requires CNC machine tools in top condition. Regular preventive maintenance in line with OEM recommendations ensures wear is minimized and accuracy and repeatability remain close to the as-new condition. Process capability assessments are useful for establishing the variation inherent in a particular movement or operation.

Tool Presetting

Accuracy in machining depends on the cutting tool tip being in exactly the right position. This is done by using top quality presetting equipment that transfers offsets directly into the CNC machine tools.

Material Quality

Workpiece material properties, especially hardness, can have an effect on the precision achieved. Higher hardness increases tool and machine deflection, altering the machined dimensions. The effect is small but when tolerances are tight it can be significant.

Hardness testing of incoming raw material is useful for verifying compliance with standards and determining the variability within a batch. Purchasing from qualified vendors is important, and in the most critical cases it’s worth requesting material certificates.

Inspection and Test

A precision machine shop should be equipped with an extensive range of measurement equipment, from hand tools and gauges to sophisticated apparatus like coordinate measuring machines (CMMs). For some machined parts customers will also want testing to ensure functionality. Pressure, leak, and non-destructive testing (NDT) are the types most often requested.

Measurement apparatus will include:

• Hand tools: Calipers, micrometers, height gauges, thread gauges and plug gauges (for bores).
• Profilometers: These measure surface form, from roughness to waviness.
• Optical comparators: Produce a magnified “shadow” image that allows measurement of small features like screw threads.
• CMM: Generally large, and always extremely precise, these machines can execute complex inspection programs. Using either touch probes or non-contact sensors, they establish the dimensions and relationships of important part features.

Two types of NDT equipment are used in machine shops, mostly for crack detection. These are magnetic particle and eddy current.

Pressure testing and leak testing are performed on parts like valve bodies and housings. Leak testing is typically based on decay of a vacuum drawn or pressure applied. For less critical applications immersion may be sufficient (bubbles indicate escaping air) while at the other end of the spectrum helium leak testing provides the highest sensitivity.

For the highest levels of precision, it’s important that inspection and test devices are calibrated to national standards. This will be addressed in the QMS.

Impro: A Leader in Precision Machining

Success in high precision machining takes commitment, discipline, and an extensive range of high-quality machine tools and inspection equipment. If you’re looking for a machine shop that can meet your needs for “perfect”, or close to perfect, metal components, these are the characteristics to look for.

Impro undertakes precision machining in a range of alloys for customers in industries from aerospace to automotive. Contact us to discuss your needs and get a quote.