Coe Press Servo Feed
Equipment Boosts Production
By 66% and Slashes Setup Times
for Cylinder Manufacturer

Just like the cylinders that they produce, their manufacturing process was under pressure. By replacing its outdated air feeds and coil handling equipment on one of their stamping press lines, Manchester Tank and Equipment Co. (Elkhart, IN) reduced manpower; increased production; and slashed setup times.

Manchester Tank and Equipment Co. was founded in 1945 and is the largest North American manufacturer of cylinders and tanks for propane, chemicals and compressed air. Products produced at their Elkhart plant include Department of Transportation approved steel and aluminum cylinders ranging from 1.4 to 28 gallons. Customers and applications include original equipment manufacturers, gas-grill producers, recreational vehicles, air compressors, forklift trucks, fire-suppressant systems, refrigeration equipment requiring chlorofluorocarbon recovery, and rail cars.

Manchester's aluminum line of cylinders are primarily used as fork lift tanks with an average run for any of the different cylinder sizes of about 300 a shift. Roughly 7,000 cylinders a day of all sizes are produced in two assembly manufacturing lines.

Steel cylinder tops and bottoms are round blanked on a stamping press and drawn into larger cup shapes. The tops are assembled from two parts, and have multiple holes already stamped into the pieces to attach the valves in a later operation. Even though most of the welding is done by automated machines at Manchester, and the company builds most of its own equipment for this, a manually operated spud welder is used to weld the valve fittings to the cylinder's top.

Major Stamping Improvements Realized

Steel and aluminum cylinder fabrication begins with flat steel coil or steel coil stock with a thickness ranging from .082" to .130" for blanking or drawing. To produce the cup shape of the tanks, the operation uses three 300-ton hydraulic presses for forming and one 400-ton mechanical press for blanking. One of the presses punch the blanks from coil stock and then draws it into cup shapes. A hydraulic blanking press is fed by a cross feeder that moves the coil stock back and fourth in a zigzag motion to get the maximum amount of metal from the coil. Then secondary operation presses draw the metal, punch holes, and produce flanges. These cupped pieces are then cut on the bottom in trimming presses to even out the lips and any irregularities in the bottom that were caused in the drawing process. The pieces are then formed to put a flange in the bottom of one of the cup halves so that the top and bottom pieces will fit together later when they are pressed together and welded.

Manchester needed to boost production, cut setup time, and reduce manpower on a stamping line that was using a 300-ton, variable-speed mechanical Minster press to produce a 44" long part that is blanked, shaped into a ring and used on the bottom of the tank for stability. This steel part is produced in a 2-stage progressive die. To do this, they decided to eliminate their air feed and coil handling equipment, replacing them with servo roll feed and coil handling system from Coe Press Equipment (Sterling Heights, MI). Operations Manager Jerry Burton said they installed a Coe coil handling and feeder system in April, 2003. In this operation they immediately increased productivity by 66%.

Previously, an air feed had to grip the stock for this part three different times to get it through the press. Burton said this hurt quality and production speed. "The new Coe servo feed was capable of moving the stock through the press with one feed stroke and allowed us to continually run our press."

He adds, "With the air-feeder inconsistencies, the fastest that we would run a product would be 30 strokes a minute, probably running high 70's low 80's in our efficiency percentage. Now I can run at 50 strokes a minute, a 66% increase in production and well above 100% to 110% for efficiency."

To get this productivity, Manchester purchased a CPRF-S224 ServoMaster Series 2 Roll Feed (for up to 24" wide stock), a CPTT 2410 threading table, a CPPS 250 24 power straightener and a CPR-PO coil reel and coil car with a 10,000 lb. capacity.

Coe's servo feeder also helped Manchester with set up speed by minimizing adjustments. "We can actually adjust the servo feeder on the fly. With the air feed, we would have to shut down production, manually measure the part's length, adjust the air feeder and tighten the feeders grippers back down, and check to see if we were within tolerance," remarked Burton.

With the air feeder, their average changeover could take half an hour. Coe's Servo Feeder lets them changeover in about five minutes. "Everything is programmed into the SmartPac controller. We just punch in the product number, and automatically bring up the coil-feed progression."

Coe's equipment has saved Manchester one man per shift and they were able to cut back to one shift. Also, since they never had a coil car before, this equipment has allowed them to reduce the crane and operator time used to move coils. "We are able to pre-stage our coils on the coil car to keep a job running more efficiently or pre-stage for the next job. Now an operator just needs to advance the coil car onto the reel," Burton added.

A threading table has helped them manage their coil threading process. "Our operator had to lift the coil from the floor into the air feeder. Sometimes heavier coils needed two operators to do it safely. The threading table has made it a one-man operation. He just needs to guide the coil into the feeder speeding our process up tremendously."

Another important feature of the Coe equipment is the feedroll pilot release. Burton said, "The pilot release is a necessity with progressive dies. Before the Coe equipment, we just had a manual limit switch adjustment for it. The Coe equipment is all programmable and more consistent in opening the rollers and allowing us to align the coil easily. This allows for any setup inconsistencies, and lets us speed up our process, because we know exactly when the rolls are going to open up for the pilot pin to do its job and align the coil."

On the Coe stamping line, foot rings and collars are produced along with a flat forklift collar that is used on all of their steel forklift tanks. Job changeovers are done two or three times per shift. Depending on the product, lot size is anywhere from 2,000 to 10,000 per day. Foot rings are the companies largest lot size, because they are used on all their products.

Putting It All Together

During assembly, the top and bottom tank pieces are pressed together with 800 lbs. of pressure and tack welded. These pieces have been pre-flanged for a press fit. After the tack weld they are set on a conveyor. Cylinders are then placed in an automated seam welder with a laser aligning/tracking system that automatically joins the halves using TIG welding (MIG for steel). This system with controls by Jetline Engineering has a laser optical camera that follows the seam of the two pieces and perfectly welds it with the process displayed on a TV monitor. The foot ring (allows the cylinder to stand up) and top collar (a shield for the valves and integrated carrying handle) are also attached at this time.

Some cylinders have a rough mill finish while others have a smooth one produced by shot blasting for cosmetic purposes. These cylinders are pressure tested at up to two times their service pressure, which can be up to 800 PSI for some designs. Each cylinder's tare weight is then written on it in an automatic process using a Telesis Pin-Stamp marking system. Next, the cylinder is low-pressure tested at about 200 lbs. of pressure and checked for leaks. They are then cleaned, have their valve-covers installed, powder coated, and have safety and instruction stickers added before they are placed on a pallet for shipping.

For steel cylinders, the process is the same with automatic welding used whenever possible for better welds. One of the differences in this line is that the empty cylinder weight is stamped on the side according to DOT regulations. Cylinders are also annealed in an oven (temperature about 1150 degrees) to even out the steel's strength.

Currently Manchester is working towards a lean manufacturing facility using a three-year plan. They have three buildings in Elkhart, IN producing parts, and they want to move all of the equipment from these facilities into one plant. They are focusing on reducing inventory while producing products faster, better and smarter.

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