Portable Metrology Makes Smith & Wesson's Day
ROMER Inc.'s Laser Scanning Inspection System

Top brass at firearm manufacturer Smith & Wesson wanted to batten down the hatches on any area of production with a negative pull on profitability. Nick Shah, manufacturing engineer at Smith & Wesson, was tasked with finding an industrial inspection solution that would streamline their forging operations, an area with high scrap rates. After an extensive period of benchmarking, Smith & Wesson purchased an integrated solution consisting of a laser scanning inspection (LSI) system from ROMER Inc. of Wixom, Michigan, and PolyWorks point-cloud processing software from InnovMetric of Quebec, Canada.

Typical forging tolerances in this industry are plus or minus 0.020 in. The inspection system provides accuracies of 0.002 in. to 0.004 in., well in range of the target accuracy. The accuracy specification of the laser scanner is 50 µm, and the accuracy of the articulated arm with probe is 25 µm; therefore the entire solution accuracy is approximately 75 µm (about 0.003 in.).

The main component of the handgun is the carbon steel frame, which is forged in lots of 500–1,000. There are three work shifts at Smith & Wesson. Before each shift begins a production run, forgers first make a sample trial run of five to 10 pieces. The forger walks a cooled setup frame over to the inspection room. The part is then mounted on the fixture for scanning. Using the ROMER LSI system, the scanner is held perpendicular to the part and the entire surface of the frame is digitized within three scans, which takes less than five minutes.

A 3-D solid model of the handgun frame is used as a reference for any new forging. The PolyWorks IMAlign module evaluates the point cloud and creates a PSL file. The data is then aligned roughly to the computer aided design (CAD) file. The software proceeds to pull up key reference points for a precise alignment of the CAD model and scanned part.

Smith & Wesson can interrogate parts in PolyWorks as never before. They can analyze 18 different calipers, six different cross-sections, 12 mismatch points and more. They can also dissect parts, and conduct geometric dimensioning and tolerancing (GD&T). To date, they have automated inspection templates in PolyWorks to inspect all of their revolver frames models. One by one, the engineering team is updating all CAD drawings from 2-D to 3-D solid models for PolyWorks analysis, and matching up target points along the way.

"We can use the system for any inspection or measurement task you can imagine, especially in the machining environment," Shah says. "Our end game is to consistently create good parts and provide solid dimensional data by scrutinizing all of our drawings, parts and CAD files which must conform. We will next move into each machining phase, utilize that data, move into the machining centers, and modernize the entire forging shop floor. The ultimate goal is to eventually move all areas of production into the digital realm."

In machining, the name of the game is to eliminate waste and reduce material usage on forgings. Delivering less material on a handgun frame would reduce machine run time, lower tool usage and increase production rates. The ideal scenario would be to pass a frame over to the computer-numeric controlled (CNC) machining process that is within 0.001 in. to 0.002 in. of the allowed machining window tolerance.

Since deploying the inspection system, the forging area is already making progress in scrap reduction. "Our goal in this department is to get our scrap rate down to almost nothing," says Joe Dombkowski, forge manager. "Just a few years ago, our scrap per unit produced was 12 cents. In this fiscal year, we have lowered the rate down to 2 cents per unit produced. Percentage wise, we have made substantial progress. This is due to the new inspection system, the experience of our forgers and better practices in place to spot possible problems."

"This technology is helping us in many ways," says Larry Flatley, business manager of specialty services. "We're focused on early detection of inconsistencies in our manufacturing processes, and this solution makes our forging process almost foolproof. When we consider return on investment on this purchase, we have reduced setup time on inspection by nearly 40 percent. We have tried other measurement methods with hard gauges and layouts with less than satisfactory results. Also, those tools do not support design changes readily, which was another drawback.

"Reverse-engineering has shown us how we could get to a better part. This is what sold me on the inspection technology. Using digital data, you speed up the process and there is less chance of error. We save hundreds of thousands of dollars when an error is caught early in the process. The cost savings in decreased inspection time and reduced scrap in this department alone has paid for itself in less than one year."

ROMER Inc.'s Laser Scanning Inspection System

Benefits:

• Overall system accuracy of 75 µm
• Portable CMM collects more than 23,000 points per second
• Works with point-cloud processing software to evaluate and align scanned data

http://us.romer.com