SUCCESSFUL METALWORKING SHOP FINDS LOWEST COST MACHINING BAR CAN BE HAZARDOUS TO YOUR WEALTH
13 November 2003 - Carpenter Technology Corporation

Utilizing the least expensive material for machining stock, without due regard for value, can be a big mistake, warns John Nolan, president of Quality Plus Precision Products, Victor, N.Y. In fact, he suggested, such a practice can drain profits severely, even totally if the shop has to invest an excessive amount of its own resources to get the results it requires.

Quality Plus, which constantly seeks ways to add value to its own products and services, abandoned its own penny pinching ways of selecting machining materials in the mid-nineties when Nolan took over the company. Results driven, he focused on the gains possible by using value-added stainless machining bar from Carpenter Technology Corporation, Reading, Pa., instead of whatever was lowest in material cost alone.

Since that change in policy, the CEO figures he has saved 'hundreds of thousands of dollars' in manufacturing costs. Even after discounting the higher cost of Carpenter's premium stainless, known as Project 70+, he estimates that he has been saving about 20% in real part costs every year!

Soft Costs

Quality Plus, a highly successful shop which recently added 25 new multi-spindle Davenport screw machines to its already impressive battery of 35 Davenports and eight CNC machining centers, has developed its own proprietary method of studying shop costs. It starts with the familiar hard costs, but also includes the soft or hidden costs which rarely, if ever, are fully documented.

Without a good handle on these soft costs, Nolan observed, many shops may not realize the cause of some manufacturing problems, or know their extent until they become quite serious.

Nolan has established a formula for studying the use and cost of his own company resources when machining parts for customers. He has fine tuned process controls and monitored costs precisely. He checks the cost of downtime related to materials or any other factor. He documents the cost of pulling worn tools, grinding or replacing them, resetting and requalifying them, and is quick to spot trends. The cost of machine setup and re-setup do not escape him. His system quantifies the cost of machining jams and machine breakdowns due to the material worked, or any other cause. It tracks the cost of obtaining close tolerances and superior surface finishes. The cost and cause of all maintenance are examined closely.

Before using Carpenter's Project 70+ grade Types 303, 304 and 316 stainless steels, Quality Plus painfully measured the substantial costs of machining economy stock, from different sources, that was inconsistent from lot-to-lot and heat-to-heat. The company then cost accounted the extra effort required of its manufacturing operations to maintain efficiencies.

'It was frustrating,' Nolan complained. 'We were continually resetting machines, tools wore out prematurely, we couldn't maintain tolerances or finishes. We had to keep changing speeds and feeds. Our productivity goals were beyond reach. We were constantly chasing variations in the machining stock at considerable expense.'

Variations in the original bargain-priced stock used by the shop, Nolan recalled, were so bad that 'our uptime and productivity would drop 30 to 50 percent, and sometimes to just about zero.'

Quality Plus depends on highly skilled machinists and technicians using fast, productive and well maintained machines, to produce its line of high quality, precision-machined parts to generally demanding specifications. Thus management places a premium on maintaining high employee morale and performance. In the same vein, employees take great pride in their work.

Human Factors

Nolan quickly recognized that the company was risking a cost and quality penalty early in the steel price shopping era. He knew it when a foreman, frustrated with poor machining stock, begged 'Why can't you get us the good stuff for this job?' The 'good stuff' the foreman referred to was a trial lot of Carpenter's Project 70+ machining bar the shop had just run.

What's the use of investing in training programs if 'you limit the performance of your skilled craftspeople with inferior materials and equipment?' Nolan asked. 'You undermine morale, breed unrest and productivity lags if the employee feels you are not allowing him or her the satisfaction of doing their very best.'

In his production process studies, Nolan has developed a method of estimating the cost of operator frustration, declining morale and consequent performance, contending that such costs are real in many shops, but rarely measured. As he puts it, 'We look under, below and between the lines for any other hidden factors that could affect our success.' This approach, he continued, 'puts us in an absolutely superior competitive position' when bidding on jobs and fulfilling contracts.

Here are just a few of the company's good results when using Carpenter's stainless steel machining bar with improved machinability characteristics:

Quality Plus enjoyed a 60 percent increase in tool life when machining valve stems from 1½'-dia. Carpenter premium quality stainless Type 303 machining bar on a CNC turning center. The stems had been used for pollution control valves used in heavy trucks. More than 1' of material had to be removed from the feed stock at consistent, high rates to reduce the stem to 3/8' dia., while holding dimensional tolerances of +0.0001'/-0.0003' at critical locations. After upgrading from its original economy stainless to the Carpenter stainless steel, the shop was able to increase its machining speeds from 450 sfm to 600 sfm, and boost its metal removal rate from 0.009' to 0.013' per revolution, with a 0.150' per-side depth of cut. Cutting tools were from both TIN-coated high speed steel and similarly coated high cobalt tool steel. The shop was able to produce more than 100 parts before a tool change was needed. Prior to the change in material, the shop averaged 62 parts.

When it was using the lowest cost stainless Type 304 machining bar available at the time, the shop had to employ three 5-spindle Davenport screw machines to keep up with demand for panel fastener screws. Forming, sizing, hollow milling, threading, knurling and cutoff operations had to be performed on the 5/16'-dia. screws. After switching to Project 70+ Stainless Type 304 from Carpenter, the company was able to maintain more than the required volume flow of parts on two of the three machines. The shop thus freed up the third machine for other work, while improving its output.

At one time, Quality Plus was unable to make, or even bid on some parts because it could not efficiently and economically obtain the fine finishes and tight tolerances required. It was able to achieve the necessary level of machinability when it switched to Carpenter's Project 70+ Stainless Type 303 with enhanced machinability characteristics. Furthermore, the company was able to establish and maintain a pricing advantage because it knew what to expect from each subsequent lot of machining bar.

Quality Plus had problems with drill life, productivity and burring when it machined a small elbow for a medical gage from economy stainless Type 316 machining bar. This part had to be formed, sized, side milled and cross drilled on a Davenport multi-spindle screw machine. Drilling was difficult because the holes intersected. The 3-fluted drills, made from TIN-coated cobalt high speed steels, would heat up, leave burrs at the hole intersections and slow production. The burrs had to be removed in a secondary operation, while the cutting edges of the drill wore prematurely. After switching to Carpenter's Project 70+ Stainless Type 316 machining bar, the shop enjoyed three times longer tool life, eliminated burrs from drilling and the need for a secondary deburring operation, and improved productivity substantially.

Working from day one with Carpenter's Project 70+ Type 303 alloy, the shop has been able to meet very tight dimensional tolerances of less than 0.001' when working stock on multiple-spindle automatic screw machines. Such tolerances, noted Nolan, are not easily and consistently achieved on this equipment. His machinists, in addition, have been able to achieve an 8 RMS finish or better, with burnishing, on components for a high-end electrical device exposed to view with a mating polished component.

Quality Plus produces precision parts in high volumes from carbon steels as well as stainless steels, mostly in sizes of one inch or smaller. It utilizes CAD/CAM technology, statistical process control to monitor quality and operates in compliance with QS 9000. The company certifies its suppliers on the basis of quality, delivery performance and price, in that order.

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