Lean Manufacturing Puts OFS in the Driver's Seat
OFS' investment in automation is helping its chair manufacturing Plant 11 transition to lean manufacturing, thereby saving time, money and manpower.
By Karen M. Koenig
Time is at a premium at the 140,000-square-foot OFS chair manufacturing plant in Leitchfield, KY. Working two shifts, the 105 employees at the plant manufacture components for hundreds of different chair styles sold in showrooms and retail stores throughout the United States.
All within a six-day lead time.
According to Eric McMichael, Plant 11 manager, implementation of the lean manufacturing concept has enabled workers there to eliminate unnecessary labor - and time - from the production process. McMichael defines unnecessary labor as any operation which does not add value to the product.
"We started with 800 [tasks] on the floor, and we were able to cut it down to 150," he says. "The throughput has not suffered. We moved some of the older machines, purchased some new technology and were able to eliminate waste in returns and manpower."
Automation Speeds Production
One of the elements of a traditional lean system calls for cellular layouts with a balanced material flow. McMichael says the plant is working toward that goal.
Currently, lumber for the components is cut to length on a Whirlwind saw, then sent via a conveyor, with a turntable, to a Raimann ProfiRip KM310 gang ripsaw. "Anyplace where we can eliminate or minimize motion, we will do so," McMichael says.
Adjacent to the other saws is a large Paul ripsaw system for removing defects from the lumber. The saw is used in conjunction with a WoodEye system, which scans for defects and helps optimize the cutting process. As part of the plant's transition to lean manufacturing, the Paul ripsaw has been set up to offload directly onto a conveyor, which feeds the processed lumber to one of the plant's five moulders.
A Weinig Unimat 3000 CNC moulder is a recent acquisition and features automated adjustment on setups and PowerLock tooling, which is an adaptation of HSK tool design for moulders. According to McMichael, the machine can process material at speeds of 88 feet per minute.
"We run a lot of chair parts through the moulders, especially if the part is going to be exposed," McMichael says. The plant has "thousands of profiles" in stock and can make and sharpen knives in-house. All other cutting tools, including blades and bits, are outsourced.
Carbide tooling is used on a Byrnes/Bacci five-axis CNC router with automatic toolchanger. Its twin tables enable the company to rout two parts in a single setup, McMichael says. Also in one setup, the CNC router can perform various other processes, such as drilling, mortising, tenoning, milling, five-axis contouring, or carving elements onto chairs parts.
A three-axis Kitako CNC router also is utilized in the plant to rout components. Other equipment on the shop floor includes a WIGO profiler, Costa planer/sander and Timesavers 2300 finish sander.
To make the curved backs, a popular feature in many of OFS' chair styles, solid wood is steam bent on a specialty machine purchased from Europe. "The wood is steamed, pre-bent, then put into a mold to keep its shape while it cools," McMichael explains. Depending on the size of the part, approximately 40 pieces can be bent in an estimated one-hour cycle time.
Almost 100 percent of the components manufactured at Plant 11 are solid wood, primarily poplar, maple, cherry, aspen and walnut, says Bill Elder, yard and lumber sales manager. The small portion of plywood and composite wood found in the chairs is for internal use only.
That all changed in 1983. In reaction to the squeezing profit margins affecting the residential furniture industry, company President Hank Menke turned his attention to the commercial wood furniture market.
And so began the successful reign of OFS.
Today, OFS is a vertically integrated company, providing rough milling, dimensioning, veneer layup, finishing, upholstery and assembly services at its various plants. Kiln-dried lumber is supplied for internal use as well as for sale to other companies. Products are shipped via a fleet of OFS-owned trucks.
In addition to office chairs, the company's product line includes: conference tables, credenzas, desks, workstations, cabinets, bookcases, lecterns and sofas. OFS does import some products, including a selection of chair frames, but assembles and finishes these items in-house.
According to Elder, almost half of all orders are customized in some regard, including upholstery, finish, wood species, or product size/dimensions.
"We're basically a custom shop," Elder adds. "All of our plants are very flexible."
This production flexibility, combined with a dedication to customer service, is reflected in the company's 10-Day Express Furniture program. OFS guarantees shipment of the product within 10 days of receiving the order.
Its commitment to customer service also helped OFS earn an OFDA Dealer's Choice award for sales and marketing. The award was presented by the Office Furniture Dealers Alliance at NeoCon 2004.
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