Screw Machine Shop Integrates Efficiency, Quality, and Diverse Services
Using highly efficient cells, a full-service shop combines the speed and precision of CNC Swiss automatics with a variety of production, secondary, and inspection capabilities.
Just-in-time delivery has had a major impact on how manufacturing is handled in North America. The trend toward ever-increasing precision, small-volume production runs, and quick turnaround has forced contract manufacturers to be mindful of ways to activate cost-efficient methodologies. While many job shops have created a narrow, specialized niche to answer the call for more economical manufacturing, others have taken a broader, more generalized approach to production. One is Northwest Swiss-Matic, Inc., a QS-9000-certified screw machine shop in Minneapolis, Minnesota, that grapples with the challenges of the global economy by providing a multitude of generalized part types and configurations very quickly.
"We are a very diverse screw machine shop in many ways, especially in terms of our equipment," says Jack Graeber, president. "Since there's not one machine that's good for every part, we decided many years ago to create a very extensive collection of equipment to handle almost any type or size of part."
It's not just the company's equipment that is diverse, but also the types and sizes of parts that the firm produces, the volumes that it cranks out, and the varied marketplace that it serves. Although most shops specialize in one size of run, Northwest Swiss-Matic routinely performs small, medium, and large production runs. And, while most job shops specialize in large or small parts, the company produces a very diverse range of sizes, supplying parts from 0.010 inch to 2 3/4 inches in diameter, and from 1/16 inch to 16 inches in length.
Cell System Expedites Production
The cell production system, made popular by Japanese manufacturing firms, is one method that Northwest Swiss-Matic utilizes extensively to expedite production. "We can handle small runs of as little as a dozen parts cost-effectively with the cell system," Graeber insists. "The system gives us a lot more control and eliminates a great deal of wasted motion. For one customer, we make 36 different serrated shafts; they all start out with the same size and type of material, but some need cross drilling or milling. This part is cost-effective because the machines are always set up for these parts, and we run parts on a continuous daily or weekly schedule."
Graeber explains that the firm's normal turnaround is about 20 days for the average medium run of about 5000 to 10,000 parts. The machine shop's average large run could be in the hundreds of thousands, or in the millions, for a particular part. Northwest Swiss-Matic has one part that is assembled into an automotive brake system, which is produced in the cell system. It machines about three or four million of these parts per year, with the run divided equally during the 12-month period. "We run these brake parts every day," Graeber discloses. "Before we started using the cell system for these parts, the best we could do was four weeks on a completed shipment. We now deliver the shipment in one week. So I think the cell system has made the deliveries about 75% quicker," he continued. "We've also brought our anodizing vendor into the cell team, which has helped them expedite our parts. Before getting involved, they were taking three to five days to complete their work; now that we work so closely, they often do the same parts in one day."
In order to control costs these days, Graeber says that the company doesn't keep a large inventory of material in stock. At one time, it was running many parts ahead of schedule, with no guarantee that a customer would purchase the parts. The contractor now works closely with customers to determine appropriate scheduling, so material is only ordered as needed. One material scheduling method in place is the Kan Ban ordering system. For example, a customer might request 100,000 parts that will be doled out in 25,000-unit lots every 90 days throughout the year.
For various reasons, Northwest Swiss-Matic now requires a written guarantee that the customer will purchase the full amount of parts, which are kept in Northwest's warehouse until requested. Northwest will then ship a specified quantity of parts weekly or monthly, depending on the OEM's needs. To more closely control production, two full-time people handle production planning with an enterprise software system called Vantage. The system, designed specifically for machine shops, helps production planners and clerical personnel control almost every production and administrative function in the plant. It also generates reports and statistical analysis data for forecasting purposes.
Early Ties with IBM
Gordon Martin started Northwest Swiss-Matic in 1962 with four cam-operated, Swiss screw machines. His son, Lee Martin, is now CEO of the company. When Lee's father initiated operations, the company's largest customers were IBM, Control Data (a manufacturer of mainframe computers), and 3M. At the time, Minneapolis-St. Paul and much of southern Minnesota was the Silicon Valley of the United States. In the '70s, many of the computer-related companies moved to California.
"Much of our early direction had to do with IBM being in Rochester, Minnesota," Graeber remembers. "Back then, they produced a lot of office equipment like copy machines, typewriters, and adding machines, so they needed a lot of metal hardware, especially shafts. In the '60s, there was still a lot of mechanical equipment, unlike today with mostly electronic technology in use. So our work has changed quite a bit over the years."
The venerable company now has customers in five major markets in 26 different states. Its primary markets are automotive (brake parts, electronic transmission, and power steering parts); fluid and air controls (spools, sleeves, pistons, and valves); medical (parts for resuscitation equipment and medical instruments); consumer appliances (shafts, valves, and pins); and telecommunications (pins, shafts, and connectors).
The company started out in a 1000-sq-ft building, but now has 50,000 square feet of manufacturing space and 8000 square feet of office space. Northwest Swiss-Matic began operations with six employees and now has approximately 100, who operate 60 pieces of primary equipment and 60 pieces of secondary equipment. Company managers operate two, 10-hour shifts Monday through Friday, and a weekend shift.
Multiple Technical Abilities
Northwest Swiss-Matic utilizes an abundance of primary screw machine equipment, including single- and multiple-spindle machines, CNC and traditional Swiss machines, and Escomatic wire machines. It also makes use of an extensive array of secondary equipment, like CNC chuckers, grinders, hones, burnishers, milling machines, drill presses, thread rolling machines, machining centers, and tumbling and cleaning equipment. In addition, the company has a vast assortment of testing, measuring, and inspection tools, both computerized and manual.
The company will work with almost any kind of metal; however, stainless and carbon steels, aluminum, brass, copper, and titanium are machined most often. With only a few cam-operated machines still in operation, the company no longer grinds many cams in-house. However, it still has an in-house tooling department for fixtures and cutting tools.
Although the per-unit production cost of a screw-machined part will usually be higher than with other manufacturing processes, Graeber says, screw machining has a relatively low tooling cost. Tooling costs for cast, stamped, or molded parts are often expensive, even for minor revisions. Another difference, Graeber says, is that a customer will never pay $50,000 or $60,000 for tooling on a CNC screw machine; and, after production commences, tooling changes are relatively inexpensive. For use on its manual, cam-operated multi-spindles, the company purchases generic, off-the-shelf tooling that rarely exceeds $2,000 in cost, although it sometimes reaches a maximum cost of $4,000 to $5,000. On its CNC single-spindles, the only charge is about $150 to cut a new program tape.
The company's CNC chuckers are used for both primary and secondary operations, where the company will sometimes run difficult, small-quantity jobs on them because of their easy programming features. These machines can also hold close tolerances very well, so they are often used for secondary operations such as boring or milling. If a part needs a large amount of material removal, it will first be placed on the multi-spindles. Then, precision, finishing tasks will be performed on the chucker.
Re-engineering to Save Costs
Besides offering a high level of technical expertise, Northwest Swiss-Matic provides sophisticated customer service. One example is the re-engineering of a three-piece check valve assembly for the power steering unit of an off-road-vehicle. When the screw-machine company was given the assignment, one part in the assembly was judged to be very difficult and expensive to manufacture.
First of all, the OEM, Eaton, was having trouble finding someone willing to manufacture the part, and second, the cost was prohibitive. Northwest Swiss-Matic's engineer decided to talk to engineers at Eaton after finding that the part was over-designed. After brainstorming, Northwest helped them to redesign the part. Due to the complexity of the part, Eaton would have had to pay over $10 per assembly with the original design.
"By making the changes that we suggested to them, we were able to make the part manufacturable and get the cost of the assembly down to about $2 per part, an 80% savings on the total cost of the assembly," said Graeber. "So our engineering assistance is a vital, value-added service we can offer our customers when they have engineering challenges."
In another instance, the company discovered that it had saved capital over many years for Woodward Governor, a customer that assembles motor governors and power generating equipment.
"After a cost study for Woodward, we found that we had not raised the cost at all on 75% of the parts we've run for them since 1992," Graeber pointed out. "Therefore, considering rates of yearly inflation, that's about a 25% cost savings overall. The study proves that we try very hard to keep down costs for clients whenever we can," he concluded.
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