Selecting the right machine tool for your company or for a specific job can be a daunting task. For more insight on this process, check out our previous article on this subject.
I’m going to assume that if you’re reading this, you’ve either purchased a CNC machine in the past or you’re thinking about purchasing a CNC machine. If not one of those, maybe you have some strange fascination with qualifying stuff. Whatever it is, it’s important to make sure what you purchased is what you received, that it is installed properly, and that it does what it says it can do.
A CNC machine purchase is exciting because we are planting another income producing asset on our shop floor, which if done correctly, should immediately increase company revenue by a % of the current revenue. If it is a more advanced machine, it will also increase your capability, which opens the door for new business opportunities and hopefully greater efficiencies.
Installation of the Machine The machine installation is straight forward for most folks but before the machine arrives, make sure you have adequate floor space, that adequate power is available at the panel, that a power drop is in place and ready to connect, and that an airline drop is in place and ready to connect. Check with the machine tool builder for power requirements for the CNC machine and all the ancillary equipment that comes with the machine (robots, bar feeders, high pressure units etc.). Some of these units can have power draw requirements equal to the CNC machine itself.
Installation Qualification (IQ)
Installation qualifications are the testing and the documented certification that the criteria for correct machine installation are fulfilled as defined by you or your organization. Prior to doing anything with the machine, and Install Qualification is performed to make sure the machine that was quoted & ordered, is the same thing that was received. You can think of this process as an Incoming Inspection. Your machine quote, and purchase order, should have a line-item list of all the machine options that were purchased as well as all the tooling that comes with the purchase.
The IQ process is to go line by line and reconcile the machine quote with the machine purchase order. Secondly, to go line by line and reconcile what has been physically received with the purchase order.
For the sake of speed and accuracy, I take the line-item list on the digital purchase order, and copy them over to my IQ form, so it would look similar to the text below, although just more extensive.
□ 2 [571-51] Front drilling unit ER16
□ 1 [0R121] Drill sleeve ER16
□ 1 [0R122] Drill sleeve ER16
□ 1 [0R144] Boring sleeve 1/4 inch
□ 1 [0R145] Boring sleeve 3/8 inch
□ 1 [0R146] Boring sleeve 5/16 inch
For the control and the electronics, the process gets a bit more tedious, because we want to make sure the options purchased are turned on, but I use the same process line by line process (see image 2). It’s a good idea to do this with the service technician still at your facility to help with verifying machine options.
□ 93278005 Spare M code: 2 pairs
□ 93278102 Constant Surface Speed Control
□ 93278137 Cs Contouring Control version
□ 93278103 Spindle Speed Fluctuation Detection
□ 93278139 Manual handle retrace function
On final step to complete for IQ, while not directly related to the machine, but good practice, is to ensure that the incoming power is within the machine tool builders specified range on each leg. Modern CNC machines and electronics have very strict power requirements, deviations from these can cause a host of intermittent and difficult to diagnose problems. Because of this, you will want to have your electrician check these at this step, and document them on your IQ form.
Operation Qualification (OQ)
Once the IQ is complete, we will use a similar process to complete the Operation Qualification. The OQ is the testing and the documented certification that the criteria for correct machine operation are fulfilled as defined by your organization or you. This step is straight forward, but it can also be as detailed as you choose. It’s rare for a machine to not function as intended, but it does happen.
The idea with the OQ is to ensure all major machine components are fully functional and operate as intended. This may include things like the machine control, the machine mechanical systems, the safety equipment (interlocks), and the CNC machine program. It’s a good idea to have a CNC program ready to go in advance of this step.
Process Qualification (PQ)
Process Qualification is used to evaluate the adequacy of the machine design and to determine if the machine design can produce parts at the projected cost and quality. This step usually involves producing at least two different parts within certain guidelines. It is because of the PQ that we recommend supplying the same parts to the machine tool builder at the quote stage, to have them run a time study. We then use those same parts (assuming that we can) to run our PQ using the prescribed process that the manufacturer specified at the quote stage.
Guidelines for Projected Cost & Quality often include:
Quality level such as 1.33 Cp (4-sigma) on certain features (OAL OD, ID, etc.)
Parts must comply with internal “Workmanship Standard”
Parts must be machined at a steady state operation for a determined amount of time with <5% downtime (DT) and < 1% scrap.
Again, you can incorporate your own parameters into this step with the goal of making sure the equipment will process parts as stated.
If you have any questions about the IQ, OQ, PQ process, or would prefer to have an outside expert perform the process for you, please contact us at email@example.com.