Design engineers are demanding faster turnaround from suppliers in order to bring their systems to market faster. To meet this need, Zero-Max, a world leading manufacturer of couplings and motion control products, has reduced its blackening time from 5 days to the same day by installing an automated, "first of its kind" Tru Temp® CNC finishing system.
Providing Zero-Max with many efficiencies, this in-house system not only is much faster, it has lowered part finishing costs from 20 cents to 4 cents for each component. In addition, it has completely eliminated all of the "hidden costs" previously experienced when sending components outside for hot oxide finishing, according to Ron Neff, Zero-Max vice president of manufacturing. Without having to add labor, Mr. Neff reports, the automated Tru Temp finishing system provides consistent high quality black oxide finishes and has even helped reduce machining center setups on select components.
Improving on its processes and delivering its products to customers in a timely manner has been key to Zero-Max success for over 50 years. By being responsive to customers' changing needs with innovative product designs and exceptional service, Zero-Max has grown into a worldwide motion control solution provider. Its products serve the most advanced and demanding industries including wind power generation, military vehicles, packaging systems and machine tools, to name just a few. To improve its product deliveries, Zero-Max recently identified its outside black oxide finishing as an area for improvement.
"We constantly examine new technology to improve our processes, quality and responsiveness to customer needs," Mr. Neff reported. "Our product lines are growing continuously and the requirements to manufacture them also change. We did a preliminary study recently to see how much time and expense our existing hot oxide finishing was costing us."
"We were astonished to find that we issued nearly 400 purchase orders in one year for outside finishing. We averaged about 50 parts per order. So factoring in the cost of the finishing, time to issue a PO and following it through to the vendor and making payment was costing us around $240 for each purchase order. That didn't take into account the hidden costs such as grouping and wrapping parts to be sent out, lost time waiting while parts were away for finishing, receiving, sorting, inspecting and redistributing parts for assembly once they were returned. Another major hidden cost was machining center setup time for parts that needed a final machining operation after blackening. Doing a study of all of these factors led us to look into installing an in-house automated black oxide system."
Collaborating with Tru Temp manufacturer Birchwood Technologies and automation builder Unifab Corporation, a first of its kind Tru Temp CNC finishing system was proposed to handle Zero-Max in house black oxide finishing needs.
"We did a cost-payback analysis showing that at our present production levels we'd have the automated system paid for within 18 months," reported Mr. Neff. "In today's competitive manufacturing environment, automation is the name of the game. The automated system would allow us to do our own black oxide finishing without adding labor. The Tru Temp process itself was key because we required a quality finish but we did not want the hazards and pollution associated with a traditional hot oxide process. Tru Temp is a low temperature, non-polluting process with a high quality black oxide finish. Factoring in these benefits plus the hidden costs we'd eliminate was compelling for the Zero-Max board to approve the project."
Design, build and startup of this first of its kind Tru Temp system took less than 3 months. The system utilizes a programmable hoist to automatically process iron and steel components through the Tru Temp low temperature black oxide process in a 28 minute cycle from start to finish.
Ruggedly designed for high volume continuous service, the line consists of eight process tanks and ten stations overall. Each station (tank) measures 24 x 40 x 28 inches made of white polypro. Two of the tanks are heated and have a steel encapsulated girth. Supports under the top lip of each tank are included to handle the extra weight of the flight bar when the hoist drops off a load of parts. Setdown saddles automatically center part loads accurately within each station. Process stations are laid out in a sequence that utilizes the same station at the front of the line and a dropoff station at the other end. In this way, the hoist picks up a load of unfinished parts, processes it through the appropriate chemical stations, then drops off the finished load at the other endo of the line. The hoist program can process up to 6000 lbs of parts per eight hour shift.
The hoist and welded steel superstructure has a 500 pound capacity. The system operates by Allen Bradley PLC digital control with a manual joystick backup. The hoist controller has a separate control panel utilizing a touch screen programmer. The system is powered by a AC single speed motor/brake with nylon belt lift. Process tanks are pre-plumbed with half-inch water lines and ball valve controls.
Zero-Max parts requiring the black oxide finish include coupling and torque limiter components made of 1215 steel. The Tru Temp finish is ideal for these components because it produces a satin black magnetite coating just 0.5 microns thick (20 millionths) with no effect on part dimension or material hardness. The finish withstands up to 100-200 hours of neutral salt spray (ASTM B 117) or several hundred hours of humidity (ASTMD1748), (verified by independent testing). The high level of corrosion protection is important for both dealer storage and ocean shipment which meets Zero-Max product finish requirements.
The present program produces two loads per hour and has the abilitiy to expand to 5 loads per hour by processing up to three loads concurrently.
Since the line was installed less that a year ago, Zero-Max black oxides between 100 and 500 motion control components per eight hour day. To facilitate part handling for processing, Zero-Max utilizes ingeniously designed wheeled carts that carry a rack loaded with up to 60 parts. Thre racks are loaded with raw parts in the deburr/parts washer department by the operator in this area, then wheeled into the Pickup station of the black oxide line. Once in position, the hoist sense its presence, the automatically picks it up for processing. The pre-programmed hoist moves the load through the correct sequence of chemical stations, then deposits the finished load in the Dropoff station. From this point, the load is wheeled to inspection/assembly by the operator from this department. In this manner, the black oxide line itself requires virtually zero labor input. The process is highly repeatable and produces black oxide finishes of consistently high quality.
To minimize part movement, the system is located between machining centers and assembly cells. Since the process is automatic from start to completion, no monitoring is needed other than simple observation when a part load is completed and moved back for finish machining or for assembly and packaging. Part handling is thereby kept to an absolute minimum.
The Tru Temp process is designed for long bath life without the need for routine dumping. At Zero-Max, solution monitoring and control is performed Monday mornings by a department supervisor. Taking less than a half hour, it is achieved by using a color change test which indicates proper concentration level. Because the process contains no EPA-regulated chemicals, there is no need for waste treatment equipment in Zero-Max's new installation - just pH adjustment prior to to discharge directly to city sewer.
There are a lot of benefits and savings with this system," reports Mr. Neff. "We've cut black oxide costs and reduced component inventory levels based on the new lead times brought about by the same day finishing. That frees up cash for other uses. But the most important benefit is eliminating the 5 day turnaround time and getting product to our customers faster. Both Birchwood Technologies and Unifab provided on-site training for our personnel. Our parent company, Miki Pulley, is very impressed with the system so much so that they are considering adding similar systems at each of their two plant locations in Japan."