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Quick changeover for a job includes breaking down the bar loader as well as the machine. Guide sleeves on the LNS loader are segmented, making them quick to remove and replace.
Using a programming system developed by Marubeni, plant manager Matt Nolan is able to simplify shop floor programming of families of parts. In one example, 12 different part numbers for a single family can be accessed by entering only one offset dimension into the macro Mr. Nolan created. The operator does this on the shop floor.
All of the parts shown here and many more that Highland makes come off the machine burr-free and ready for cleaning. "Cycle times may be a little longer to program that extra pass to clean a bore, but overall the savings in handling are worth it," says owner Mark Erickson.
For the right application, Swiss-type turning centers can enhance and expand a shop's turning capabilities. In some cases, shops find the Swiss-type work so plentiful and lucrative that they abandon conventional turning altogether and concentrate exclusively on precision Swiss-type work. Highland Products (Mentor, Ohio) is an example of such a process-focused shop.
Founded 26 years ago by president Mark Erickson, Highland has grown by learning turning technology from manual engine lathes to full CNC multi-axis Swiss-types. Every technology step along the way has served as a process of elimination for Mr. Erickson.
"I approached CNC Swiss-type turning from a different direction than most turning shops I knew," says Mr. Erickson. "Having worked with conventional turning centers which usually required secondary milling, drilling and tapping operations, the versatility of the Swiss machine to do all of these operations in a single part handling was a huge leap in processing capability. With the application of bar loaders, we can set up these machines to run for extended periods unattended."
Today his shop is fully focused on workpieces that are no more than 1.25 inches in diameter. Highland runs several of its 11 CNC Swiss turning centers 24 hours a day, seven days a week with a shopfloor staff of four.
This shop has learned how to get more parts through the shop faster using a minimum of internal resources. Running lights out is an important part of this shop's operation. But it took a while to get there. Hard learned lessons to be sure, but lessons that are now paying off in the form of a successful precision part making business.
A Mentor In Mentor
Like many job shops, Highland started out humbly. Mr. Erickson's technical qualifications consisted of an interest in machine tools based on exposure to them in high school and not much else.
"Twenty-six years ago when I started out here in Mentor," says Mr. Erickson, "I didn't know how a shop ran. I knew nothing about workflow. I didn't know what a shipper or a PO was or anything about throughput. My metalworking business background was very thin. Basically, I could run a manual screw machine, engine lathe and Bridgeport mill."
Young Mr. Erickson was a good machinist. One of his first customers took this fledgling businessman under his wing and taught him the machine shop business.
"It was my first customer who put me on the map," recalls Mr. Erickson. "He explained to me how work should come into the shop and flow through it. He defined for me what a purchase order was—basically a signed contract that I would make parts to a specification and deliver them on the date promised. He even went so far as to give me his stationery and scratched out his company name and I put mine in its place until I had forms printed for my company. He was a tremendous help to me in the early days."
Highland's first CNC machine was a Pratt & Whitney Star-turn. Mr. Erickson learned to program it and got in work to keep the machine busy. The company then bought a big Okuma turning center. It too was busy making large workpieces, many of which needed a crane to load and unload.
At that time, Highland was still doing smaller engine lathe work. "I was killing myself trying to keep the big machines fed with work and at the same time running the shop, getting in work and helping set up the small jobs," recalls Mr. Erickson.
"I basically backed into Swiss turning," says Mr. Erickson. "A customer in the medical field had a part for me to make. Initial quantity was 15 pieces. I cranked these out on an engine lathe. Then the customer came back with an order for 500 of these parts per month. The customer suggested I look at a Swiss type turning center. I bought my first Citizen. That was almost seven years ago."
Before Mr. Erickson took delivery of the machine, the order was canceled. Who hasn't had that nasty experience? So Highland went into a scramble mode to find work for the new machine that was by far the most expensive piece of equipment in the shop.
As Mr. Erickson tells it, "I had a $4,000-a-month payment to make on a machine that had no work. That's scary. A neighbor job shop had a hydraulic piston that it was having trouble with and gave me a shot at it. I asked the distributor who sold me the Citizen lathe (Concentric Corporation, Cleveland, Ohio) to help me set up the new machine to run the part. Happily, the third part we ran was in spec, and we were subsequently awarded a contract for 2,500 of the hydraulic cylinders. It was a tough part requiring an overall spec of 0.001 inch and a tolerance of ± 0.0005 inch on 40 grooves which acted as oil seals on the cylinder—no O-rings. The shop I got the job from had been making these parts on a conventional lathe in two operations, using false centers in a cycle time of 25 minutes. They also had to use a second operation to remove and clean up the false centers. We made the part complete in 88 seconds. I made my first machine payment in one day's production, and since then the machine has never been without work."
It was about this time that Matt Nolan joined the company as plant manager. "He was literally an answer to my prayers," says Mr. Erickson. An expert in CNC Swiss-type turning, Mr. Nolan helped get Highland deep into the processing nuances of sliding-headstock machining.
After about three years with Mr. Nolan doing the Swiss-type work and Mr. Erickson working the conventional turning centers, they decided to concentrate the business on Swiss-type work.
"There are 12 machine shops in the industrial park where we're located," says Mr. Erickson. "Prices are so low now for conventional turning centers that almost anybody can buy and set up and run an 8- or 10-inch chuck diameter turning center. There is simply too much competition in this size of work."
Highland is a job shop. It has an active customer list of 90 companies. Job lot quantities range from one to one million parts. Scheduling this kind of variety is essentially a juggling act.
A benefit that Highland derives from its CNC Swiss machines and their LNS (Cincinnati, Ohio) bar loaders is the ability to quickly tear down and set up any job. "We often changeover a single machine five times during the day shift," says Mr. Nolan. "We try to book the shorter run jobs during the day while our machinists are available, then put on a long run for the night and graveyard shifts. It's a balancing act because not every job can or should be run unattended."
Highland started practicing unattended machining with a contract they received from another local shop. It was a shaft part 23 inches long and 0.5 inch in diameter.
The finished part weighed about half a pound. The bar loader they had at the time could only hold enough stock for about 120 pieces.
"We would set up the job to run," says Mr. Erickson, "and set the machine's part counter at 120. That gave us several hours of unattended production. I'd come in once during the night to re-load the loader and check the last part then reset the counter for another 120 parts and run until morning. Eventually we fabricated a "Z" shaped rack that could hold enough bar stock to eliminate the night re-load."
Picking Unattended Jobs
While choosing a given job to run lights out is far from formulaic, there are some general guidelines that Mr. Nolan follows in his selection process. These jobs generally run on three of the shop's 11 machines unattended.
"Workpiece material is the first consideration," says Mr. Nolan. "We want a free-machining material such as brass or leaded materials. Pre-hardened steels actually run better than some softer materials because they machine freely."
Geometry of the work is the next consideration. "Tolerance is a more critical consideration than complexity," says Mr. Nolan. "Often a geometrically complex part with numerous features fits unattended operations well. Its longer cycle time puts less strain on tooling and bar loader capacity. Jobs with overall tolerances below ±0.0003 inch will generally need some operator intervention to verify no drift in accuracy has occurred. Above that tolerance, we feel comfortable running lights out."
Chip control is critical to successfully running unattended. Highland equips its lathes with high-pressure oil applicators to keep the workzone flushed. "Selecting the right cutter geometry helps keep `bird nests' to a minimum," says Mr. Nolan.
A reliable bar loader system is also a critical factor for unattended machining. "We turn down the ends of our bars," says Mr. Erickson. "On a pusher-type loader, this allows us to use a bar loader collet that's no larger than the bar. In turn, the guide bushing can be sized closer to the bar OD. Closer tolerance between the guide and bar provides better support and reduces the tendency for the bar to vibrate, which can cause chatter in the workpiece."
Accurate and consistent bar stock is an often overlooked variable when shops try to run unattended. "Many shops try to save a little money on the purchase of bar stock for a job," says Mr. Erickson. "For a few dollars more, I'd rather know that the bar will machine consistently and that there will be no size variations between bars. Controlling variability is the key to automating a process."
First, Dim The Lights
Highland has learned that no matter how well you plan a job, something almost inevitably goes wrong. Rather than set up a job, turn on the machine, and walk away only to have a bin of scrap waiting for you the next morning, Highland phases in new jobs with a series of trial runs before going full lights out.
"Before we turn off the lights to run a new job we first dim them," says Mr. Nolan. "We'll put the job on a machine late in the day and run it attended for a few hours and unattended for a few. After the job runs a while, we look for any weak links in the process such as a tool wearing too fast or program glitches. All that takes about a day of prove-out. Once the process is stable, we run all night."
Technology Is Key
In any job shop, keeping the machines loaded with work is a critical factor to success. That implies sufficient capacity to manufacture the work.
"The old job shop paradigm is to grow capacity by adding spindles," says Mr. Erickson. "We found that for us, upgrading to current technology can be a better way to increase capacity."
As an example, at one point Mr. Erickson was replacing three of his early Citizen lathes. These machines were three, four and five years old respectively. Highland ran a comparison between the older Citizens and the new one, which had just been installed. In just five years, the new machine was 30 percent faster than the older model.
"That test clinched it for me," says Mr. Erickson. "In just those few years, the change from hydraulic to electromechanical actuation and from microprocessor-based controls to PC-based had increased this machine's performance by 30 percent. That additional productivity spread over several machines means that three machines can do the work of almost four older machines. That's increased capacity." Highland's oldest machine is now about three years old, and plans are to replace it.
Turning over machines on a more frequent schedule has produced some unforeseen benefits for Highland. For one, "trade-in on these two- and three-year-old machines is much higher," says Mr. Erickson. "We realized a return between 60 and 70 percent. That lowers the out-of-pocket expense for the new machine."
With the warranty in force on new machines, Highland has little or no maintenance expense. "Another advantage of trading-up frequently is that our machinists can more easily make the adjustment to running the new machine because it's not too far removed, technologically, from the older machine," says Mr. Nolan.
Of The Body
Mr. Erickson can make parts on his shop's machines. He doesn't have to today because the shop has hired and trained its small staff to take responsibility for their machines and all of the process variables that go with them. But everyone knows the boss has the ability to make parts.
At Highland, machinists program, set up, prove-out and inspect all of their own work. They have ownership. Mr. Erickson and Mr. Nolan function more as coaches than managers. Mr. Nolan's programming expertise is applied to new jobs and optimizing existing jobs. The system works well for this shop.blog comments powered by Disqus