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CNC punch press aids group-technology team.

CNC punch press aids group-technology team

When Austin Dental Equipment Co, Newberg, OR, purchased its first Amada Pega 344 CNC turret punch press six years ago, the company was at a crossroads. Demand for its line of dental equipment had increased to the point where existing fabricating equipment could not produce precision parts at sufficiently high volume. The company had to do something to keep its dominant position in the field.

Bob Emmerich, director of manufacturing, explained, "The Pega was the first piece of computer-controlled equipment we purchased. The success or failure of that venture would determine how our company would proceed in the future."

"We looked at several different CNC punching machines, went to job shops, and talked to programmers," says Walt Shuey, production manager. "We looked at quality, reliability, and availability of service.

"Before we purchased the Pega 344, we completed our punching on three hand-operated pieces of equipment. We still use them for simple, low-quantity jobs, and for easy setup. But, for most of our work, we need the capacity that a CNC machine offers.

"The Pega 344 is five to ten times faster than our manual machines. Nevertheless, the volume of our sheet-metal parts pushed the machine to full capacity, leading to a decision to purchase a second Pega, the Model 345 King with automatic indexing. It runs at 275 hits/min (hpm), with nibbling speed of 475 hpm, giving us a 30- to 40-percent increase in production."

Extra punch duty

The auto-index feature enables each punch-and-die set to rotate through 360 degrees under numerical control during press operation. Thus, just a few punches can handle a large variety of complex shapes. Rotating a punch set to serve at many angular settings has the same effect as increasing the number of available punches.

With auto index, it's possible to cut complex forms from a single worksheet, thus reducing the labor of subsequent operations. And, it allows programming of micro-joints that remain even after circular punching. These make it possible to produce a large number of circular pieces automatically without stopping to remove each one.

Finally, the auto-index feature can produce shapes that nibbling cannot, and it means a considerable cost saving over standard nibbling.

Getting your teeth into it

Shuey explained that sheet-metal parts are used in dental chairs, dental furniture, and dental units, the latter being delivery systems that include the dentist's controls and instrumentation as well as instruments for his assistant.

"Dental units generally need a chassis to hold wiring and controls, and most of these are made of aluminum--some stainless steel," says Shuey. "In fabricating a chassis, we start with a 16" x 144" sheet and shear it down to 16" x 24". The programmer works from a blueprint, and puts it on tape, so we can feed it into the Pega. It takes an average of 2 1/2 hr to do a program.

"We can get many parts from a single large sheet. We punch holes in each chassis section, then cut out each corner, there is a sliver of metal holding the piece together. When the sheet comes out, the operator shakes the sheet and the parts drop out easily.

"Parts then go to a finishing operation for removal of burrs and sharp edges around holes. They also receive a satin finish. Next, they go to a press brake for forming, and on to a separate facility in Portland, OR, for anodizing. Back at our Newberg plant, each chassis goes to final assembly, followed by mounting in a dental unit."

Group technology

In 1980, Austin Dental Equipment Co (A-dec) became interested in two new manufacturing concepts: group technology and quality circles. Management toured facilities throughout the US that used these concepts, then developed their own combination of the two, called A-dec Business Units.

Bob Emmerich explains what happened. "We shifted to group technology from a traditional shopfloor plan arranged by types of machinery. The new setup uses a layout based on similar parts or assemblies being produced by a group of people in one location. This concept is also referred to as Family Parts Manufacturing or Manufacturing Cells.

"Basically, our business-unit plan gets people working together as a team and gives them responsibility for a complete job. We do not have a QC department. Every person is responsible for his or her own production."

What kind of an impact did the Business Unit have on production? Shuey reports, "Before using the concept, we required 13 weeks of leadtime--from the time the sheet metal area got the work order to completion. Since we've been using the Business Unit, we've reduced that time to four weeks!"

How does the Business Unit operate? "Part numbers are assigned to individual manufacturing families for processing. Each supervisor receives orders with required due dates and arranges them for processing within the family. Each family group has the machine capacity to produce the required quantities of parts. Families order and receive their own raw materials and store them beside the machines that use them.

"Machine arrangement generally is in a flow-line direction: parts start at the first machine and move straight through the area to completion. Family members move around to the work location and concentrate on keeping a continuous flow of parts through the area.

"Once an order is started, it continues to completion. If an order needs to be expedited, it's placed at the head of the line. This allows the Business Unit to maintain a continuous flow of parts with a minimum of scheduling conflicts."

Are there other benefits? "We have better communication on all levels, and more employee participation. For example, one of our fabricating people suggested that we sand and anodize the parts before we shake them off the sheet. That idea and the employee's participation cut anodizing costs from 85 [cents]/part to 15 [cents]/part.

"I believe it was the combination of the Business Unit and the efficiency of the punch press that brought out the creativity in this person. Our people are involved, and they know that they are the most important element in our company."

PHOTO : A-dec Production Manager Walt Shuey (left) checks quality of bends with Bob Emmerich,

PHOTO : director of manufacturing. Bending is done on Amada FAB 80D press brake.

PHOTO : Azalia Hernandez assembles a dental unit.
COPYRIGHT 1989 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1989 Gale, Cengage Learning. All rights reserved.

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Title Annotation:computer numerical control
Publication:Tooling & Production
Date:Oct 1, 1989
Words:1051
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