CAM And Turn/Mill: Making More With Less
A shift in thinking has led to an overhaul of this company’s machine tools and production processes. The result has been a significant improvement in capacity that has allowed more parts to be brought in-house and more profits at the end of the day.
“Our machinists are excited about the prospects of bringing in a new machine now.”
That’s not always the sentiment when a shop’s management starts making significant changes to the equipment on the floor. Often machine operators can be quite apprehensive when they learn that the machines they’ve become experts on and the processes under which they’ve been operating will soon be replaced. But at Norriseal (Houston, Texas), such changes have brought excitement to the job, with increased capacity, significant productivity gains, more efficient workflow and a positive effect on the company’s bottom line that every member of the organization can benefit from.
Patricia Lewis, operations director, goes on to explain that although the company has an aggressive executive staff that tries to move forward with processes in the factory, shop personnel were not always so flexible. “We are very engaged with our customers; we frequently bring them to our facility so they can learn about our company and its capabilities. But we sometimes lacked in capitalizing on our biggest asset—our people. We had a machinist at each machine. It wasn’t until we brought in a new manufacturing engineer, who had a fresh perspective and started to question the procedures, that we revitalized our approach to improving efficiencies of our people, processes and equipment.”
Roots In Oil And Gas
Founded in 1955, Norriseal is a manufacturer of valves and controls, serving predominantly the oil and gas industry, but also a range of other industrial markets. The company was acquired in 1962 by Dover Corporation, operating in the Energy Products Group in the Fluid Management segment. Bob Funk, company president, notes that being part of Dover, with its understanding of manufacturing companies and financial resources, enables the company to move forward with its strategic plans. Norriseal operates out of the 75,000-square-foot headquarters, with about 100 employees working in engineering, manufacturing, customer service and technical support. This facility takes raw material to finished product, including all manufacturing, assembly and testing. Sales and support services are also available through a global network of representatives.
A great deal of machining takes place at Norriseal, including turning, milling and grinding work. Material is primarily 17-4 and 316 stainless, in barstock and castings. In recent years, the company has begun to take a good, hard look at which machines are pulling their weight and which ones should be replaced with newer technology; which tooling solutions are most effective and which are leftovers from days long ago; and generally, what operational methods can be applied to maximize resources.
In 2006, the investments in machining began with the purchase of a 600-mm horizontal machining center and a CNC lathe. The success of the first two machines also highlighted the need for a new manufacturing engineer. In July 2007, Norriseal hired David Bickerdyke as senior manufacturing engineer and charged him with refining the manufacturing process within the organization. Mr. Bickerdyke was aggressive in applying his experience to eliminate the less productive equipment, implement lean manufacturing strategies and motivate the employees by engaging them in production decisions. Within 14 months, the company had retired 11 machines from the shop floor, including mills, engine lathes and screw machines that were each more than 20 years old. In their place came three Mori Seiki machines—a dual-process CNC turning center, another CNC lathe, and most recently, an integrated turn/mill center. This latest machine has created the most excitement throughout the factory.
The turn/mill was brought in as a direct replacement for two other machines. As such, as many as 1,600 existing parts are currently being run on or programmed for that machine. The programs are written mostly as they are needed, but a spreadsheet tracking the part usage for the previous 2 years also gives Mr. Bickerdyke an idea of the highest-volume parts that are most likely to be needed next. “We’ll work on parts that are in immediate need first,” he explains. “When those are complete, we’ll go back to the spreadsheet to determine which parts we can work ahead on. So we’re always programming, but we’re finding huge savings with that machine.”
The savings can be clearly seen with a typical part—a butt plug machined from 17-4. This part was previously run in five operations—two on a lathe and three on a vertical mill. The setup time for those two machines was a total of 6 hours, and cutting time was about an hour and a half. Worse still was the time the parts would sit lined up in front of machines, between operations, awaiting the next step. Running one of these parts often took more than a week. On the turn/mill, setup is 45 minutes and machining is 45 minutes.
“One reason this machine works so well for us is the 40-tool magazine,” Mr. Bickerdyke says. “An OD turning tool, which is turning on the main spindle, can also be rotated 180 degrees to cut on the subspindle. You can rotate it 90 degrees so it can bore as well. So on this part, we face, bore, spin it around, finish, spin it around again and go the other way, all with one tool.” Also on the turn/mill are two 12-inch Schunk quick-change jaw chucks—a hardened base jaw and a soft jaw on the top. On the main spindle are three sets of hard jaws that provide a 12-inch range. They repeat within about a half a thousandth.
It’s In The Programming
Another reason Norriseal has had such success with its turn/mill center, as well as its other machines, is the programming process it uses. The company uses Edgecam software from Planit Solutions. Mr. Bickerdyke first explains the general reasoning behind using the software offline. “There’s no way we’d spend that kind of money on a machine only to offload it to a guy on the floor to spend time programming. While he’s programming, the machine’s not productive. Besides that, he’s trying to catch interference on the fly, and that’s just asking for trouble.”
Instead, while the machine is running one part, other parts are being preprogrammed in an office. Simulations are run on the computer screen to catch potential crashes before they can cause real problems.
Norriseal has been using Edgecam for several years, but recently upgraded to Solid Machinist, a module of the CAM system for generating milling and turning machining strategies and NC code from solid models. This version uses automatic feature recognition to interrogate the solid model and quickly identify machineable features. The software then offers the user the most appropriate tooling and machining strategy to generate accurate tool paths.
“We’ve been doing a lot of these jobs for years, so solid models did not exist for them before,” says Mr. Bickerdyke. “We didn’t need them before we had the turn/mill center because it was basically 2D machining. With multi-axis machining, though, we need a model. We import mostly from SolidWorks, but files from any major CAD system can be used.”
Mr. Bickerdyke makes extensive use of the PCI (parametric command interface) feature as well. The PCI is a quick script like a macro file that he is able to write for certain processes that he needs to program on a regular basis. “These can bring programming time from 45 minutes down to about 10,” he comments. “It quickly grabs your tool, all your comments, your rapid moves. We take a program and specify what we want by highlighting how we want to face and rough turn and that sort of thing. It works similar to a Microsoft Wizard or a template for our operations. It makes the process more predictable.” This predictability is particularly beneficial when more than one programmer is involved. “Even if a new person comes in who’s used to programming a certain way, the PCI forces him to do it our way. We have a template to work with that is consistent from one part to the next and one person to the next.”
Also contributing to fast and effective code generation is the Edgecam Code Wizard application. This feature allows programmers to configure code generators using a simple template that provides the basic structure of the CNC control. It then prompts the programmer to make minor adjustments to the code to get the exact output required. “The Code Wizard is great for troubleshooting,” Mr. Bickerdyke points out. “You can use a code constructor trace, and it will break your code down into separate sequences, allowing you to see exactly where the problem is. Then it steps you through the changes and, when complete, it updates the post processor.”
Part of the changing philosophy at Norriseal has been to engage everyone in the company in the process improvements. On a programming level, this has meant providing the machinists with a new perspective—they now have Edgecam right at the machine. A PC with a student edition of the software is installed at each machine. This version is fully functional except for posting permissions. When the operator gets a job, he takes the appropriate folder to the machine, scans a barcode, and the program is downloaded directly to that PC via a wireless network. If the operator is not familiar with the job, rather than studying drawings, he can simulate it right there to see exactly what the tool is going to do. “This gives the operator a lot more confidence,” says Mr. Bickerdyke. “He can see right there what the programmer did.” The company plans to eventually have a PC at every machine.
This connectivity has also allowed the company to implement a shopfloor monitoring system from Predator Software Inc. that keeps all personnel in tune with the production process. Separate from the CAM software, Predator MDC (machine data collection) collects, reports, charts and processes shopfloor manufacturing data in real-time. Machine data collection improves manufacturing by supplying accurate shopfloor productivity metrics to improve operations and to make better decisions.
Norriseal has a monitor mounted on the wall in the middle of the shop floor that displays the status of all of the machines, which parts are running and the number of good parts and bad parts. This display, which is customizable with almost 240 different reports, can be viewed from any PC throughout the shop. Other data relating to each machine, operator, part number, downtime and efficiencies can also be accessed. Larry Williams, vice president of finance, explains the system’s potential: “Some could view this as a way to monitor machinists. I see it as an opportunity to integrate a business system and have real-time understanding of exactly what it takes to produce parts, for costing, quotation and process planning. If I ran a job shop, I’d have this in an instant. For us, doing a lot of standard products, it helps us to prove out old standards and verify our projections for shopfloor productivity.”
Innovative approaches such as these have been fundamental to Norriseal’s accelerated business plan. Since Mr. Bickerdyke’s arrival less than 2 years ago, manufacturing throughput has increased by more than 10 percent, already surpassing the company’s long-term goals. On-time shipments and leadtimes have also improved significantly. Ms. Lewis comments, “As an executive staff, we attribute many of our shopfloor improvements to the contributions of David and the equipment and programs that he has brought to the company.”
Although the effects are clearly linked, Mr. Bickerdyke describes the improvements as more of a shift in company-wide ideology. “It’s nice when you can be with a company that is interested in change that makes sense, and not just for the sake of change. We’ll continue to replace the remainder of our older equipment with new, more efficient machines over the coming months and years. And as we do it, our machinists continue to get more excited about the prospects. We’ve managed to bring back in-house a good deal of our work that previously was being farmed out, and our people realize the benefits of this.” But Norriseal won’t bring in-house all of its machining requirements—only what it’s good at. And something the company is clearly good at is getting the most out of its machines and personnel—more with less.
— DMG MORI USA