Most contract manufacturers claim they produce "quality" parts. But how can you find a quality-driven shop capable of handling your specific requirements for machined medical parts? The key is to look for a shop that practices value-added quality methods such as validated process control. Such companies are organized and structured to a high degree and have strict control of their policies, processes, and procedures, backed by extensive documentation. Here are the critical questions to put to a potential supplier or find the answers for yourself.

Does the company have a QMS in place?
For purposes of discussing QMSs, let's first clarify the terms "verify" and "validate." Consider this simple analogy. If you are building a medical device, you use objective techniques to ensure that all the parts in the device measure according to the drawing specs. This verifies that everything meets specs. On the other hand, validation of the whole process of building the device comes from using or operating it. The end result is the device performs as intended.

Today, many shops are certified to ISO 9001, a basic Quality Management System (QMS). However, shops machining medical parts should be qualified to advanced QMS standards such as the ISO 13485 Medical Device standard and the AS9100 Aerospace standard. Both contain ISO 9001 in its entirety.

A shop adhering to ISO 9001 must identify its processes and then document, monitor, and measure them. Here, a “process” is defined as a set of interrelated or interacting activities that transforms inputs into outputs. Examples include purchasing, machining, deburring, cleaning, and shipping.

A breathing circuit was CNC milled out of stainless steel.

The ISO 13485 Medical Device standard and the AS9100 Aerospace standard each also expand upon ISO 9001. The standards have their own unique requirements for risk analysis, control of suppliers, process control, and identification and traceability. AS9100, for instance, requires shops to "flow down" requirements to their suppliers, so they, too, are held accountable.

Does the shop perform first-article inspection?
By necessity, shops adhering to the Medical Device and Aerospace standards must perform first-article inspections. The first-article inspection provides objective evidence that all engineering, design, and specification requirements are properly understood, accounted for, verified, and documented. Once the shop has its machining process under control and is making good parts, the first-article inspection verifies that this is indeed true.

The medical monitoring componenet for meltiplex testing was made via CNC turning.

Shops such as Aztalan Engineering up the ante a notch by doing the first article on the prototype, which — unlike many shops — is made on the very production equipment it intends to use, not on side machines. It thus starts the validation process from the beginning. When you are ready to give the go-ahead to run the parts, the shop already has the process set.

The shop might then revalidate depending on whether complications arise after the job has been running for awhile. The chief engineer might work with the programmer, for instance, to get the ideal insert so the cutting tool lasts longer.

Shops certified to the Aerospace or Medical Device standards must perform a risk assessment on the part’s processes. The main idea is to focus on defect prevention, not defect detection.

During a risk assessment, a shop zeros-in on what could go wrong at a supplier or in its own facility and then mitigates these risks by figuring out ways to correct potential problems. For example, parts made with a soft material might be at risk for a workholding problem because the collet could mar or distort parts. The shop anticipates this and looks for a solution.