photo credit: Vulture19 / Wikimedia Commons. CC BY-SA 3.0

Key Takeaways

• CMMs are critical for quality control but often act as a bottleneck, slowing down production throughput.
• The goal is not to replace the CMM but to reduce routine reliance by shifting inspections to the CNC machine tool.
• On-machine probing enables accurate, in-process inspection, eliminating delays from part transfers and rework.
• Automated alignment systems like NC-PartLocator ensure perfect part positioning without manual setup or complex fixtures.
• Real-time inspection data helps adjust tool offsets and prevent scrap before it happens, maintaining tight tolerances.
• By freeing up routine checks, the CMM can focus on final acceptance, calibration, audits, and RandD tasks.

In the world of high-precision manufacturing, the Coordinate Measuring Machine (CMM) is a cornerstone of quality control. But for many manufacturers, it has become a significant bottleneck, causing delays, eating up valuable machine time, and holding back production throughput. The constant shuttle of parts from the machine tool to the CMM for inspection is inefficient and costly.

The solution isn’t to replace the CMM, but to fundamentally change its role. By shifting routine inspection tasks to the machine tool itself, you can drastically reduce CMM inspection time and unlock a new level of efficiency. Here is a five-step plan to guide your transition from a manual, CMM-reliant process to a streamlined, automated quality control workflow.

Step 1: Identify the CMM Bottleneck

Before you can solve a problem, you must understand its full scope. Start with an audit of your current inspection process. The CMM bottleneck isn’t just the time spent measuring parts; it’s all the steps leading up to and following that measurement.

• Manual Setup: How long does it take for an operator to manually set up a part on the CMM?
• Part Handling and Transfer: How much time is spent moving parts from the CNC machine to the CMM room?
• Waiting in Line: Is your CMM often idle because parts are waiting to be inspected? Or are parts waiting for CMM access while a machine sits idle?
• Programming: How much time is dedicated to CMM programming for routine part checks?

Pinpointing these hidden inefficiencies will provide a clear, quantifiable business case for transitioning to an automated system.

Step 2: Implement On-Machine Probing

The most impactful step in reducing CMM time is to perform routine checks directly on the machine tool. Modern CNC machines, when equipped with high-precision probing and automated software, can accurately measure features without ever moving the part. This eliminates the largest source of delay: part transfer.

Instead of running a part through an entire cycle and then sending it to the CMM, you can verify critical features in-process. You can check for tool wear, confirm part dimensions, and identify potential issues before they become defects. This proactive approach saves time by preventing the creation of bad parts in the first place, thus reducing the need for CMM rework and scrap inspection.

Step 3: Embrace Automated Alignment

A major reason for sending parts to the CMM is to verify that the part is correctly aligned with the machine’s coordinate system. For complex or distorted parts like castings and forgings, manual alignment is a time-consuming and imprecise process that often leads to errors.

MSP’s NC-PartLocator and Best Fit Alignment technology tackles this issue head-on. This automated system uses probing to understand the part’s actual position and automatically adjusts the machine’s program to match it. This eliminates the need for expensive, complex fixtures and hours of manual setup. By ensuring the part is perfectly aligned before a single cut is made, you guarantee it will be machined correctly the first time, negating the need for extensive CMM inspection later on.

Step 4: Leverage Data for Real-Time Feedback

A fully automated inspection process generates valuable data. Instead of simply getting a pass/fail report from the CMM hours after a part is complete, on-machine inspection provides real-time feedback.

Data on tool wear, part deviation, and thermal shifts can be used to make immediate corrections. For example, if a probe detects that a feature is a few microns out of tolerance, the system can automatically adjust tool offsets to compensate. This continuous feedback loop ensures that the process stays within a tight quality window, preventing the creation of an entire batch of bad parts that would have required CMM inspection and potential rework.

Step 5: Re-task the CMM

The ultimate goal of this five-step plan is not to render your CMM obsolete. Instead, you’ll re-task it to its highest and best use. By shifting routine checks to the machine tool, your CMM is freed up for tasks that truly require its level of sophistication.

Your CMM can now be used for:

• Final Acceptance Checks: Performing complex, critical checks on a small sample of parts for final sign-off.
• Calibration and Audits: Verifying and calibrating on-machine probes and machine tool geometry.
• Reverse Engineering and R&D: Supporting engineering and product development teams with detailed analysis.

By reallocating its time, you turn your CMM from a production bottleneck into a powerful asset that supports a more efficient, profitable, and proactive manufacturing operation. The path to drastically reducing CMM inspection time is clear: automate what can be automated and save the CMM for what truly requires its expertise.

FAQ

Why is the CMM often a bottleneck in manufacturing?

Because parts must be transferred, queued, and manually set up, the CMM process introduces significant delays and inefficiencies.

How does on-machine probing reduce inspection time?

It allows routine inspections to be done directly on the CNC machine, eliminating part transfer delays and catching errors in-process.

What is automated alignment and why is it important?

Automated alignment uses probing to adjust programs to the part’s actual position, eliminating manual setup errors and reducing CMM dependence.

Can real-time feedback improve production quality?

Yes. On-machine inspection provides continuous data on tool wear and deviations, enabling automatic corrections before defects occur.

Does this approach make CMMs obsolete?

No. Instead of being overburdened with routine tasks, CMMs can be re-tasked for high-value work like final checks, calibration, and RandD.

What’s the main benefit of automating CMM processes?

Manufacturers gain faster throughput, fewer errors, reduced scrap, and a more efficient use of both CNC machines and CMMs.