Optical Measurement Keeps Pointe Precision Sharp

When lives could be endangered by the failure of a part, making that component takes on a new importance. "Our components are what we call "life-critical," observes Joe Kinsella, president of Pointe Precision Inc. "It means lives could be at risk if our quality fails. Consequently, we take inspection very seriously."

Pointe Precision Inc. is a one-stop machining job shop in Plover, WI. Since 1995, the company has specialized in producing critical tolerance parts of fuel control systems, primarily for the aerospace industry, and other precision parts for medical and industrial applications. A new 60,000ft2 production facility generates 3,500 different types of products each year. It's a mid-to-low volume contract manufacturing operation focused on parts with high degrees of precision and variation.

ISO-certified since 2000, Pointe Precision employs 110 people, of which 70 are highlyskilled engineers and technicians pursuing a Six Sigma methodology aimed at zero-defects quality output in less time and at a lower cost than its competition. The plant operates on a five-day, two- and three-shift schedule with some lights-out production.

When a part is processed at Pointe Precision, a feature-based inspection criteria guide is also created for every dimension at every operation. Every machine work center is outfitted with surface plates and the necessary inspection equipment to allow operators to perform consistent and reliable in-process inspection. Pointe Precision likes to point out that quality is not a department, it is a part of what they do.

On-Time, In-Tolerance

"Our customers' tolerancing is becoming very stringent," Kinsella notes. "Right out of the chute you have to deliver perfect parts. We have learned that our inspection systems must quickly and repeatedly ensure that the many critical dimensions and features on our machined parts are well within tolerances."

One of the busiest pieces of inspection equipment is a Starrett HD400 Horizontal Benchtop, Dual Lens, Measuring Projector, also referred to as an optical comparator. Optical measurement is a non-contact technique that graphically displays and measures parts with dimensions and shapes that would be difficult to measure with regular gages.

Pointe Precision has found an edge by trimming time from the production cycle for each product it produces with no compromise in quality. Their lathe operators have found significant time savings in the use of the Starrett comparator for visual verification on the shop floor.

While the plant depends on a state-of-the-art, climate-controlled metrology lab for some measurements, shop floor inspection is also an integral part of the production process at Pointe Precision. The Starrett HD400 is stationed on the manufacturing floor in the center of their turning operation, which is comprised of a dozen lathes. The Starrett comparator is equipped with a Metronics QC200 Digital Readout Device used to produce geometric dimensioning and tolerancing (GD&T) calculations.

"The Starrett HD-400 allows us to verify a wide variety of product characteristics very quickly," explains Chris Spranger, quality assurance manager with Pointe Precision. "We measure many features, including angles, outside diameters, runout, hole sizes, corner breaks, threads, radii and shaft lengths on parts measuring 2" or less.

"The Starrett HD-400 drastically shortens our in-process inspection time, as well as our changeover time between manufacturing work orders. If we were to verify all the features we measure on the optical comparator, using conventional gages instead, our inspection times would be two to four times longer, depending on the product being manufactured."

At Pointe Precision time saving expediency is frequently the mother of invention. Take the measurement of inside features of a part, for instance. To simplify the inside inspection job, they often use molding compound to obtain a mirror image of inside diameter groove widths and chamfers. A molding compound is pushed into the mold cavity. After it sets, the mold is removed and staged for measurement. This makes the interior details of the part easier to measure and reference on the comparator."

Visual Versatility

"We use the Starrett HD400 to get the measurements quickly and easily," Spranger notes. "We have also measured the distances between holes with the HD400 by placing pins in the hole for easy location."

The Starrett HD400 is a busy machine, with 12 machinists using it more than 20 times per day as they verify complex parts.

Inspectors use the Starrett HD400 Horizontal Benchtop, Dual Lens, Measuring Projector (Optical Comparator) to enlarge part features to ensure the production line is holding its tolerances.

"We like the comparator a lot," states Marty Cattanach, level 3 operator. "The quick release fixture on the table is a huge time saver versus a manual crank handle. The screen rotates very easily for checking different angles. Plus, we can check distances and concentricity with the Starrett, which we couldn't do on our previous system. And we really like the view. It has sharper, clearer optics that allow us to pick up edges much better. Before the HD400, features were very fuzzy and shadowed. The Starrett Comparator allows you to see much greater detail. It's just more accurate and much faster."

Randy Grezenski, manufacturing engineer for Pointe Precision, explains: "The Starrett comparator has more bells and whistles than its predecessor. We can take three hits of an arc, for example on a half spherical radius a 1/2" in diameter, and take three points, make a circle and establish our centerline on the part. We actually use it for some measurements that previously required a CMM located halfway across the plant in an inspection room."

The Starrett HD400 is a horizontal measuring projector that provides a 16" x 6" (400mm x 150mm) measuring range using an indexing dual lens slide, and brilliant, triple bundle, fiber optic surface illumination with dual intensity tungsten halogen profile illumination. The HD400 features a highly accurate workstage and profiles the part on a 16" (400mm) diameter screen with magnifications available from 10x to 100x. Generally, the horizontal type optical comparator works best with parts that need to be fixtured, held in a vise, or on centers.

The Projection?
Increased Throughput.

According to Spranger, minimizing setup time is a critical factor in keeping the company competitive. Some runs involve as few as 50 pieces, while others may involve 1,000. As any manager knows, setup time does not pay the bills. By placing the Starrett comparator on the shop floor in the machining area, Pointe Precision eliminated time-consuming trips to the inspection room. And if they had to inspect their precise parts using only micrometers, indicators and other conventional gages, their inspection time would be much longer.

Spranger estimates the Starrett Optical Measuring System has easily reduced overall inspection time by up to 75%, depending on the complexity of the part.

"Each one of our 12 turning centers is on ‘setup' for its next job two to seven times in a 24-hour period," Spranger continues. "On these machines, setups are usually completed between 30 minutes and three hours after they are started. Our studies have shown that 10% to 25% of the setup time is absorbed by the first-article verification process. You can easily see the impact of an inspection process that took three or four times longer to complete. The Starrett HD400 helps us minimize setup time and get into production mode quickly."

Spranger says most inspection is done at the machine and points out that the turning department not only has the Starrett HD400, but also Starrett surface plates and other gages located near the machine for use with each lathe. Even first-article inspection is frequently done on the shop floor rather than in the CMM/Inspection Room.

"We have found optical, non-contact measurement to be an integral part of our turning operation. The Starrett HD400 provides a more reliable, repeatable and far faster method for inspecting parts, including setup and the all-important first-article inspections," Spranger concludes.

When asked about the future of quality control, Kinsella believes in-process measurement and inspection equipment designed to decrease human error will become the norm. "Accuracy, zero-defects, quality control and productivity will only increase," he notes. With equipment like Starrett Comparators, it's not difficult to see that Pointe's accuracy and throughput will continue to increase as well.