March 2008 Edition

machining strategies

Southern strategy: Cut inventory while shortening those lead times

As a manufacturer, Quincy Compressor Inc. of Bay Minette, AL, has come a long way from its days assisting dairy farmers.

The origins of Quincy Compressor go back to 1920. George Gille, John Kathe, and George Wall started the Wall Pump and Compressor Co. in Quincy, IL. The company's flagship product line was a series of vacuum pumps designed for milking cows. By 1924 the company changed its name to the Quincy Compressor Co. and expanded its products to meet the growing demand for industrial air compressors. In 1937, the company introduced the Quincy QR-25, a reciprocating air compressor that quickly became an industry standard.

While Quincy Compressor sells a variety of products for the creation and treatment of compressed air, its specialty is manufacturing custom rotary screw and reciprocating air compressors with the industry's most reliable air end. The company manufactures a variety of rotary compressors, ranging from 5 to 500hp. The quiet and reliable compressors are built for 24-hour operation. Quincy manufactures 3- to 30-hp gas or electric reciprocating compressors.

Quincy serves an array of markets with compressed air systems. Reciprocating products are used in general industrial, energy exploration, medical applications and natural gas extraction/transmission and climate control. Rotary screw compressors are used in energy/petroleum, concrete/construction, printing, textiles and agriculture.

As a business operation, Quincy Compressor plays a Southern strategy today. It is headquartered at the company's rotary screw compressor manufacturing, testing, and assembly plant in Bay Minette. Some components are manufactured in the United States and sent to China for assembly and sale in Asia, but all North American sales are manufactured and assembled in the United States.

Seeking flexibility

Quincy experienced substantial growth in the industrial air compressor market over the past several years. Even so, the company knew it had to increase its market share to guarantee future growth. As a result, the company concentrated on increasing its manufacturing efficiency and flexibility to meet the demands of today and tomorrow.

"While contract manufacturing would have eased our capacity constraints, the high costs and risks of having large queues of high-precision components encouraged us to look elsewhere," says David Peed, manufacturing engineer and machining team leader at Quincy. "A more favorable option was to purchase new, more efficient equipment."

The sale volumes of rotary screw compressors were creating capacity constraints in Quincy's precision stator machining area despite efforts to balance machine loads to exploit capacity. The planned introduction of new air ends further complicated machine loading and required increased flexibility to accommodate new models. This capacity constraint was compromising the company's ability to respond to increased business opportunities for service air ends, short lead-time orders, and new product introductions.

In 1995, Quincy installed a two-machine Makino MC98 cell with 16 pallets. That cell is still running static parts, inlet valves, discharge ends, and end caps. Since this wasn't Quincy's first experience with Makino, it again turned to Makino for precision and reliability.

Precision was a serious concern for Quincy. The machining process of the air compressor housing requires four parallel bores to be machined, two from each side of the cast housing, two of which are approximately 10" in diameter and 17" deep.

"We've found that running deep, wide bores, while keeping the tolerances down to 0.001" true position in many cases, beats up machine tools pretty fast," says Peed. "The cutting forces, along with the large amounts of material removed, can wreak havoc on tooling, the spindle itself, the chip conveyors, and countless other features of the machine."

Because Quincy manufactures a complete product totally in-house, the company is its own machining customer. When machines go down or deadlines are not met, it directly impacts on-time delivery and on-budget performance. This significantly affects the bottom line and could ultimately tarnish Quincy's image.

"We're a very efficient company," adds Peed.

Complex solution

Most recently, Quincy installed a Makino Machining Complex, consisting of two Makino A88 four-axis horizontal machining centers (18,000rpm spindle speed), and then shortly after upgraded its cell to include an A88E high-speed horizontal machining center (12,000rpm spindle speed). The complete cell utilizes a 30-pallet flexible manufacturing system to improve the machining of air compressor housings and air inlet castings. An automatic 244-tool changer on each machine accommodates all the necessary tools for common jobs.

The manufacturing processes on the Makino MMC produce stator components from raw castings to finished machined components in one process. Quincy is using two of the A88s to run inlet castings, while the third is used for small rotary housings and overflow work.

Whereas the typical machine in Quincy's operations requires one operator to run two machines, one operator can run three machines in the Makino cell. Using the new Makino cell, Quincy has reduced cycle times and increased spindle utilization, capacity, and flexibility with the ultimate goal of lowering inventory levels of finished products and decreasing lead-times to internal and external customers.

"I'd say we reached those goals," continues Peed. "We reduced cycle times by 25 to 30 percent. We are maintaining process capabilities of 1.33cp to as high as 1.92cp on the Makinos. We're also impressed with the dynamic accuracies and thermal stability of the machines, as well as the rigidity of them under heavy loads."

Flexibility is key

In addition to cycle time or other measurable metrics, Quincy was also impressed with the flexibility that the Makino cell offered.

"Flexibility is the key," says Peed. "We can quickly change priority of one part and start another part on the machine without interrupting production.

Designed to improve manufacturing efficiency, the MMC2 is an enhanced pallet management system created to meet the increasing and changing demands of customers. The system assigns work and initiates operations automatically based on machine and material availability, utilizing maximum spindle capabilities and monitoring all automated procedures.

The MMC's cell controller can handle an unlimited number of parts, and can process an unlimited number of steps per part. In addition, it can handle unlimited different parts per pallet and utilizes production order management software that tracks order numbers, part numbers, quantities, dates required and priorities.

This flexibility allows Quincy to produce parts in a just-in-time manner for each order as it moves through production. To ensure automated production, Quincy also needed a local partner.

Single source technologies

Single Source Technologies partnered with Makino to help deliver the automated system for Quincy. SST served as a local resource providing engineering services, supplies, application support and customer service. SST ensured Quincy's Makino cell would be up and running smoothly without any delays in its production operation.

Installation took place in two phases to minimize interruptions to Quincy's manufacturing operation. Sales volumes were at a record high, and production levels were requiring 24/7 operation. The company had the first two machines and 16 pallets installed and started into production.

Makino then set the third machine, laid new rails, moved the load/unload station as well as the cell controller with minimal interruptions to production. Makino worked with the operators to time down periods of the cell vehicle with long run jobs inside the machines. By doing this, Quincy met all of its production demands and on-time deliveries.

In addition to reducing cycle times, the Makino cell has helped Quincy evolve its Continuous Flow Manufacturing capabilities. Since the early 1980s, Quincy has focused on CFM, a manufacturing strategy that produces a part via a just-in-time production approach, at its Bay Minette plant.

Since then, Quincy has been improving its build-to-order environment, balancing its production lines to reduce waste and cost while delivering on-time and defect-free parts. The Makino cell allows for continuous production and quick turnaround, allowing parts to pass onto assembly in the same building. The Makinos also allow for repeatable and predictable part manufacturing as orders arrive.

"The Makino cell is one of the major advancements in the machining area," explains Peed. "It has provided us with the ability to increase flexibility and throughput while reducing inventories of both raw and finished goods."

The company plans to expand its business into China, India, Southeast Asia, Latin America and the Middle East, manufacturing the compressors in the United States.

"We need to make sure all of our systems will provide the most efficient means of manufacturing our compressors, from start to finish, and allow us to ship the finished, customized product in the time our customers' demand," says Peed. "With our Makino cell, we're able to accomplish that goal and expand our business." Makino

What do you think?
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