Process Re-Engineering, Smith & Wesson Style 

Large and small, old and new, U.S. manufacturers grapple withprocess reengineering to remain viable in today’s global market. A heavy hitter in the firearms industry, Smith & Wesson is no exception. The company’s reputation for quality products standsstrong after 154 years of existence. With facilities in Springfield, MAand Houlton, ME, this thriving company of 900+ employees is on the move to reengineer its manufacturing practices, protect its frontline turf and make their bottom line shine. At the heart of this transition, portable metrology is playing a leading role.

The Search is on

Top brass at Smith & Wesson wanted to batten down the hatches on any area of production with a negative pull on profitability.  Finding the optimum tools for the job is always the first challenge. Nick Shah, Manufacturing Engineer at Smith & Wesson, was tasked with finding an industrial inspection solution that would streamline their forging operations, an area with measurable scrap rates. Shah’s search led him to a variety of trades shows, conferences and metrology vendors for technology that would provide multiple benefits for quality control. After an extensive period of benchmarking, Smith & Wesson purchased an integrated solution consisting of a ROMER Laser Scanning Inspection (LSI) system and PolyWorks software, a point cloud processing software from InnovMetric (Quebec, Canada). With the system installation and training complete in late 2006, Shah began to scrutinize a process that has created the finest guns in the world. He closely examined the existing inspection procedure, consisting of hand-held measurement tools such as micrometers and calipers. Experienced forgers also applied their keen eyes and years of experience to pinpoint irregularities or mismatching, but it was the small nuances undetected by the human eye throwing a wrench in the works.

Built for Inspection

Directly off the forging area, Smith & Wesson built a separate room for their new quality assurance equipment. Inside is a Laser Scanning Inspection system from ROMER Inc. with a 7-axis INFINITE portable CMM and a ScanShark laser scanner. This combination of articulating arm measurement with laser scanning enables maximum surface inspection of a workpiece. Next to the measurement system is a laptop computer with PolyWorks inspection software. The non-contact scanning system acquires more than 23,000 points per second for detailed inspection of both geometric and surface features. The setup also allows for point data capture with contact probes when needed. The ROMER INFINITE seven axis scanning arm has a measuring volume of eight feet. The articulated carbon-fiber arm functions with a low profile, ergonomic Zero-G counterbalance for one-handed operation. This design reduces operator fatigue for extended usage. The portability of this system was a major consideration for its procurement. The system rests on a solid granite plate atop a rolling cart that can be transported all over the factory. Near the ROMER arm is an ordinary clamp fixture used to hold handgun frames during the scanning procedure. In touch probing mode, integrated Wi-Fi (wireless) communication adds another aspect of free movement. The mobile system will prove very practical when heavy forging dies on the shop floor are inspected and reverse engineered. Typical forging tolerances are plus or minus .020". The inspection system provides accuracies of .002" to .004", well in range of the target accuracy.

Integrating Metrology into the Forging Process

Vincent Tiernan, Senior Metrologist at Measurement Solutions Group (Glastonbury, CT), has served as a technical consultant during the system implementation and continues to support metrology initiatives at Smith & Wesson. He and Shah devised a powerful, intuitive routine that would capture, align and analyze scanned data from a handgun frame, then compare the point cloud data with its related 3D CAD file. Extensive research went into devising a virtual fixture that would align the frame to the same position as it would be machined. Once completed, they created reference-based fixture data used to align the scanned data within the software program. Their template approach to automating inspection procedures introduced technology-based quality assurance to the forging department in a very straightforward manner. The same template could be utilized further for other product lines with minor adjustments to the macros. Tiernan expands, “This approach enables someone who is not a metrologist or a computer user to click a mouse and walk step-by-step through the process. You don’t have to be a software guru to inspect a part to a very high degree of precision.” Departmental adoption of any tool will only get accepted if it delivers information people need. Throughout the project, Shah worked jointly with the forging department to create the methodology that would lead to improved part production. The exercise captured a combined knowledge base of men who had been in the forging business for over 25 years. This is valuable experience that could be lost in the coming years. “The buy-in from our workforce is there,” states Shah. “We worked closely to prove out the technology, and let the forging department visualize and verify the results for themselves. One of our employees is 62 years old with no prior knowledge of Windows-based software. He is now booting up the computer, starting up the arm, and completing the inspection process on his own. Currently, three employees in forging are designated to participate in inspection. They have completed the learning program, and are all using the system well. Next, I will train the four die makers to inspect their dies.”

Inspection UnPlugged in Forging and Beyond

The new metrology solution makes the forging process visible down to the tiniest deviation. Shah and Tiernan designed the first inspection template for the 44-magnum revolver product line, as it was generating the highest scrap rate. In the past, if there were issues downstream in the machining process, the data coming back to the department could not be precisely verified. The CAD to- actual-part analysis provides a quantum leap over the hand-held measuring tools of yesteryear. The main component of the handgun is the carbon steel frame, which is forged in a lot of 500 - 1000. Before each work shift begins a production run, forgers first make a sample trial run of 5 to 10 pieces. The forger walks a cooled setup frame over to the inspection room. The part is then mounted properly in the fixture for scanning. Using the ROMER system, the scanner is held perpendicular to the part and within 2-3 scans; the entire surface of the scan is digitized in less than 5 minutes. The process feels as if the user is spray-painting a part. As the data is captured, the dense 3D point cloud can be seen on the computer screen. An audio cue guides the user during the scanning routine for the best results. At this point, the inspection template automates a 5-point process — align, inspect, output, create a PDF file, and send to file folder. A 3D solid model of the handgun frame is used as a reference model for any new forging made. It is imported into the PolyWorks inspection software. The PolyWorks IMAlign module evaluates the point cloud and creates a PSL file. The data is then aligned roughly to the CAD file. The macro proceeds to pull up key reference points for a precise alignment of CAD model and scanned part. All inspection points are then created. PolyWorks IMInspect module analyzes both sets of data and generates a visual 3D road map with a color map denoting the varying degrees of deviation. In this case, if the forger sees a predominance of red and green areas on the model, the department is ready for their production run on the handgun frame. Ninety nine percent of the time, the forger can look at the visual 3D model derived by the CAD-compare analysis, and give it a pass or a fail decision. Every hour, 3 parts are pulled for dimensional checks on 5 inspection points in critical areas of the frame. After the frame has gone through heat treating and coining, the frame is inspected once again prior to machining. Shah states they can interrogate parts in PolyWorks as never done before. They analyze 18 different calipers, 6 different cross-sections, 12 mismatch points, and more. They can also  dissect parts, and conduct GDT and primitive checks. 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 2D to 3D solid models for PolyWorks analysis, and matching up target points along the way. Eventually, they will build similar quality assurance templates for all models in their semi-automatic pistol lines. “All in all, we can use the system for any inspection or measurement task you can imagine, especially in the machining environment,” Shah anticipates. “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. Where do we go from there? We will 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.”

On To Machining

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 rate. The ideal scenario would be to pass a frame over to the CNC machining process that is within a .001" to .002” of the allowed machining window tolerance. The key to expanding inspection into machining was the forethought to create the virtual inspection fixture reference points and its critical points to replicate the fixture that would be used in the machining process. Three bedding points on the frame are critical for troubleshooting. If the frame locates properly via these points, then the machinist should have no problems. If those drilled holes are not properly executed, then the problem is compounded downstream at each consecutive phase. At the end of the day, if the critical datum — the hammer stud point — was in the wrong spot, the part would have to be scrapped. Shah is now generating the inspection template for the final check of the machined part. When a problem arises, the contest between machining and forging will soon be refereed by the inspection system. Complaints of a frame not sitting properly in the fixture, incorrect target points, or not enough material will be solved with precision technology that takes the guesswork out of the process. During this current phase of research and development, the troubleshooting has already enabled Shah to make improvements on the shop floor. “We want to analyze the A cut operation to see if parts are coming out accurately,” states Shah. “We will take a look at how critical those areas are, then move to the finish frame and compare that to the forgings. Once the bedding is proper, and the locating holes are created, we can go back to inspect the datum and find the problem quickly. If this process is accepted, we eventually want to move onto high speed machining from there.”

The Big Payback

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,” states Joe Dombkowski, Forge Manager. “Just a few years ago, our scrap per unit produced was at its historical lowest level. In this fiscal year, we have lowered the rate down to 1/6 of what it was. 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,” states Larry Flatley, Business Manager of Specialty Services at Smith and Wesson. “We are focused on early detection of inconsistencies in our manufacturing processes, and this solution makes our forging process almost foolproof. When we consider ROI on this purchase, we have reduced setup time on inspection by nearly 40%. 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 the most 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,” concludes Flatley.