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CNC improves pots and pans.

One of the oldest functions for functional containers is holding mankind's food while cooking. The shape of many of today's cooking vessels can be traced to primitive clay pots. Pots and pans as a product line certainly aren't considered "high tech."

While microwave cooking and frozen prepared foods changed the character of the market for our product, the professional and private serious chefs and cooks are more adamant than ever about the quality of their pots and pans. Cast aluminum utensils are enjoying a popularity dependent in part on their good heat conducting properties, and in part on our ability to produce attractive designs that looks as good in the dining room as they do in the kitchen.

Our manufacturing operations date back almost 100 years (1891), and we pioneered many of the advancements in aluminum cookware. Our trade name (Wagner-Ware) and city name (Sidney, OH) are cast into the bottom of pans used worldwide.

Methods are important

Although we make a full line of sizes and shapes to meet every cooking need, product simplicity means there are no design secrets to make us unique in the market. This adds importance to our efforts to use the most modern production techniques to gain a competitive edge.

Our proprietary polishing methods are the envy of others. Moreover, our anodized surfaces are extremely hard, and the products' bottoms are thick and even--they are often used on flat-typ ranges.

In a continuing effort to make the products even better looking, our VP, William Miller, came up with the idea of turning the inside contours of our pots and pans on a CNC lathe rather than applying a Sunray abrasive finish--the traditional finish for most manufacturers. The Sunray appearance is short lived because it soon wears smooth. A smoothly turned finish in the beginning has a look of quality that's consistent with the idea of a 100-year warranty.

Here's a plant tour

The best way to show the significant change this idea is making in the process of producing our product is to take a tour of our facilities and see the operations performed. Such a tour can be made with reference to the accompanying pictures.

The castings are hand ladled into permanent molds, many of which are two cavity. We use a band saw to trim the gates from the perimeter of most of the pots, Figure 1. If the casting is from a two-cavity mold, the two parts are first cut apart and then trimmed. It takes a good eye and steady hand. Trimming still is required in the new operation sequence.

Next, they go to a specially made facing machine where they are loaded on a spindle, Figure 2, and gating material left on the top face of the unit is machined off. This operation is considered the rough facing operation in the CNC method, or may not be required.

Now they are ready for contour grinding, which does the major stock removal to clean up the sides and bottom. The machine is a special design of ID grinder, Figure 3, in which the headstock that carries a vacuum chuck swings out for ease of loading the workpiece. The machine's cycle involves both the large feed wheel shown and the long lever the operator is leaning against in the photo. The amount of operator involvement in actuating this machine suggests that he must be an athlete. This operation isn't needed in the CNC method.

Grinding wheels load up and must be changed frequently. Some castings that don't completely clean up can be salvaged by hand grinding, others must be remelted. Next is the classic Sunray machine, Figure 4, in which both the work spindle and the toolhead rotate to produce the Sunray pattern. Here, a 60-grit abrasive belt is used to finish the surface, but not expected to remove much stock. It's at this point in the old method that we get our first look at the final surface of the inside of the utensil. If it has surface flaws that prevent it from being shipped as a uality product, it either must be salvaged or remelted.

This is a strong point in favor of the new CNC method. We bypass grinding and Sunray operations and go directly to the new Monarch machines. Here, the finished top face and insides and bottom are produced in one operation. If surface defects are discovered, they are not so costly since we have less work in the parts at this stage.

Our giant step forward

Before looking at the CNC operation, let's pause a moment and discuss these machines in the context of the shop. It is basically a foundry with associated grinding and polishing operations. We have no other numerically controlled machinery; therefore, we had no personnel with experience in programming, setup, and operation of such equipment.

Our previos method removed stock in the form of grinding grit. Now we produce greater amounts of chips that can be remelted or sold for a scrap value. When we eventually have a sufficient number of CNC machines to do all of our sizes of pan sets, we will generate a much larger volume of chips. (We package and sell multiple sizes of ware in one boxed set. If nay one item in the box is made by the CNC method, they all need that process ot match.) With higher quantities of chips for remelt, the question of separating them from the cutting fluid will take on greater importance. You can see that the decision to go CNC had widespread implications.

In the proposal stage we relied heavily on Ernest Hollenbacher, coordinator of applications engineering at Monarch Sidney. He arranged for trials and demos is their plant so our top management could be comfortble with the ida that this departure from tradition was workable. After we contracted to buy two of the machines, their people worked closely with ours to ensure success.

The vacuum chucks were our design, but the carbide tooling was to their specs. Setup time always has been an important concern of ours. While this is a high-volume shop, it must produce a wide range of shapes and sizes. Making 11 setups per week is routine. At first we were two to four hours setting up a new size on the new machines. Now we do it in less than one hour, Figure 5. The operator sets up his own machine and is responsible for the quality of his production.

Tooling details

The setup requires a program, the right vacuum chuck, and adjustment of tools in the tool block on the machine slide. Those familiar with the Monarch Medalist will note that the machine usually is equipped with an indexing turret on the cross slide; however, since our contouring operation is so relatively simple, we get by with a block that holds all necessary tools.

Our vacuum chucks have urethane lining on sides and bottom, with a neoprene ring to seal the bottom. Upon loading, the part generally is seated by a couple taps with a mallet. The center hole in the chuck is connected to the vacuum pump and is used also to provide a blast of air to eject the part when the machine cycle is complete.

A typical high-volume run is the 9" omelet pan, Figures 7, 8, 9. The ease of loading and unloading is demonstrated by the fact that the operator hs time between those tasks to drill holes in a handle and pan simultaneously on a table setup next to the CNc lathe. Our triple-rivelted cast-aluminum handles are safe and add a touch of class to the designs.

Note that the programs are simple. The one for the omelet pans has only 17 lines. Beverly Gehle, whose previous experience was only with business computers, learned to do the programming for these machines.

Rest of the story

Not seen are the balance of operations necessary to finish the products. Buffing is done by hand on backstand machines. Some of our people have done this critical operation for 30 years. It takes skill and experience to put our finish evenly all around the pot.

The anodizing tanks are serviced by an overhead conveyor system. Our top-of-the-line Magnalite Professional series is beautified and protected by this electrolytic bath.

Our conveyorized parts washer recently was upgraded. After washing, each utensil is final inspected before packing it for shipment.

Bringing these two Monarch Medalists on stream has been challenging. We are evolving essentially from dust and grit to coolant and chips. Our people are responding well to the planning and innovation required to keep us first in quality in an extremely completitive market. We look forward to continuing this progress.
COPYRIGHT 1985 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1985 Gale, Cengage Learning. All rights reserved.

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Title Annotation:computer numerical control
Author:Schwab, John
Publication:Tooling & Production
Date:May 1, 1985
Previous Article:Overview of abrasive-belt grinding.
Next Article:Flexible manufacturing demands flexible inspection.

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