When Quality Demands Clean Parts
A critical quality issue of many parts is their final condition after manufacturing. They must be oil-free and completely clean. Meeting or not meeting these conditions can make them usable or scrap.
A critical quality issue of many parts is their final condition after manufacturing. They must be oil-free and completely clean. Meeting or not meeting these conditions can make them usable or scrap. This is a challenge for VMP, Inc. (Valencia, California), a screw machine shop that produces thousands of parts per day.
A few years back the shop was looking for a cleaning system that would help improve the final condition of parts. "Quality was our first concern," says Bob Schreiner Jr., vice president/general manager at VMP, when describing this search for the right cleaning system. "At the time, we had a 40year old cleaning system. It was time to step up in technology."
Mr. Schreiner's second concern was durability. "During the year that we were looking for the right system, I saw 3 to 5year life spans on many of the machines we saw."
Mr. Schreiner found that special combination of capabilities, quality and durability at Magnus Equipment (Cleveland, Ohio). The parts washer provides the right amount of heat, chemical concentration, agitation and rotation to meet VMP's cleaning requirements. "With their solidstate electronics and stainlesssteel construction, I can easily foresee a 40- to 50year life span for the Magnus washing systems we ended up buying," Mr. Schreiner says.
Efficiency was a definite benefit with the new Magnus. Since its installation, the unit has helped VMP maintain a competitive product cost while offering high quality parts and ontime delivery. Its speed and quality have enabled VMP to take on more largevolume customers, which has resulted in a tripling of the company's sales volume.
A pleasant costsaving benefit for Mr. Schreiner has been the minimal amount of waste sludge left from the cleaning process on the new parts washer. After 2 years of operation, VMP has only had to dispose of 55 gallons of sludge. And in California, with its stringent environmental laws, this can be a major concern.
VMP, Inc. is a familyowned business that started in 1960. Among its customers are General Electric, Boeing and Lockheed MartinMarietta, as well as companies in the medical industry. However, the company is well known for manufacturing threaded and nonthreaded inserts and fasteners, with many conforming to MILI-45208 specifications. It has a complete line of standard inserts and fasteners for industrial applications. Engineers at VMP will design or recommend parts for their customers' requirements, providing CNC screwmachined parts from four different facilities for rotational molding, injection molding, electronics and fittings applications. Materials offered include brass, aluminum, stainless steels and Ludloy.
VMP's CNC department machines industrial parts using Acme Gridley and Davenport screw machines. The Swiss department can turn out precision parts to a tolerance of 0.00005 inch to meet the requirements of the medical industry. The variety of machines within VMP can tackle parts ranging in size from 0.032-inch diameter stock up to 3.5-inch diameter rounds or 2.5-inch hex stock.
Jobs often require VMP to cut holes and threads 0.08 inch to 3/8 inch in diameter with 3/410 threads. "We have many deep, blind holes with 16, 18 or 20 threads and a pitch at the bottom on some of the parts," explains Mr. Schreiner.
According to Mr. Schreiner, the work at VMP required a cleaning system that offered minimal rinsing requirements, left parts clean and free of chips, and prevented any rusting or oxidation of the parts. "Rotation and vertical immersion agitation allows for constant flushing to get oil and chips out of all the nooks and crannies of our parts," he says.
"Magnus understood what we needed from the beginning," he notes. "The Magnus sales representative demonstrated the new Magnus 36 SWR featuring a heated tank, stainless steel construction and a vertical immersion agitation with rotation cleaning cycle. Once I saw the machine in operation, I could tell they were going to provide exactly what we needed."
Today, the Magnus washer accepts screwmachined parts from the four VMP machining facilities.
The elements required to meet VMP's cleaning requirements were temperature, the proper cleaning chemicals and rotation, combined with vertical immersion, agitation and time. Heating the solution helps break down the oils, allowing the cleaning solution to eliminate the oil. The cleaning solution also contains a rust inhibitor to keep parts from oxidizing and rusting.
Aggressive rotation is needed to allow chips to come out of any blind holes. "With the rotation, the parts are constantly tumbling to loosen the chips. The machine we were looking to buy had to provide axial rotation," Mr. Schreiner says. A continuous immersion agitation with rotation cycle flushes the chips out. Rotation outside of the wash tank removes any residual cleaning solution or chips remaining on or in the parts.
The rinse tank features an internal electric heater. "We run a lot of brass through the machine. If I set the water temperature at 175°F while we are running at full speed, the temperature might drop down to 168°F. We don't run as hot on the wash. The purpose of a hotter rinse is to put enough heat into the part so that it flash dries once it leaves the rinse water," says Mr. Schreiner. This approach means parts don't need to sit long on the drying table, which is not part of the parts washer.
Once they leave VMP, the clean parts arrive at the customer's dock and are ready for operation. "A lot of our competitors use solvent chemical cleaning, such as perchloroethylene, which requires the parts to be dipped in alcohol before use," he adds. "Our parts can be taken right out of their shipping box and placed on the injector pin of a molding system without any additional cleaning. This is a big savings to the customer."
More than 150,000 OEM and distributor parts machined by VMP will pass through the Magnus washer in a matter of 2.5 hours. "Our older system, a vapor degreaser built back in 1960 by my dad, ran 24 hours a day and took two operators. Today, the Magnus washer handles the same workload, starting at 7:00 a.m. and finishing by 9:30 a.m. That is a dramatic improvement in time and cost," says Mr. Schreiner.
VMP is also an environmentally conscious precision manufacturer. "We make a point of recycling our waste materials. We are trying to be a self-reliant shop. We are constantly filtering oils, using chip spinners, coalescers and filters right at the machining systems." The parts washer is an extension of that environmental mentality at VMP.
One of the Magnus washing units features a coalescer on its wash tank. Spent washing solution is circulated through the coalescer, allowing the oil in the wash water to split from the soap. The oil floats to the top of the water, where a skimmer collects the oil. "We can recycle the oil and put it right back into use during machining," says Mr. Schreiner.
The Magnus washer automatically keeps the water levels to a preset level. Cleaning solution and water acidity is checked using a pH monitor and titration.
The wastewater in the soap solution is evaporated off, leaving sludge. This sludge or waste from the cleaning system consists of minute debris that collects as sediment at the bottom of the coalescer. "We have had the system in operation for 21 months now, and we are just getting our first waste stream from the operation. From the volume we are seeing, we expect to generate only 55 gallons of waste sludge over 2 years. That's nothing compared to our previous method," says Mr. Schreiner. This minimal amount of waste generation does more than provide recycled washing solutions and oil, it also saves on disposal costs for VMP. "It costs $200 a barrel to dispose of this waste," says Mr. Schreiner. Reducing cleaning sludge amounts to this level promises to give VMP savings in disposal costs.
A ventilation stack attached to the Magnus system also adds recycling capability. The ventilation system provides a small amount of draw on the parts, which removes any condensation on their insides. "This low pressure system draws out moisture from all the nooks and crannies in the parts," says Mr. Schreiner. "Then once the moisture leaves the parts and goes up the stack, we have a system in the stack to collect the water vapor and recycle that."
Magnus components are easily accessible, making maintenance simple. "We already have the unit on a maintenance schedule. It only requires maintenance 5 to 10 minutes a day. Every 3 months we do a more indepth maintenance step that can take 2 hours. That maintenance procedure involves cleaning the air lines and ensuring they are free of debris. We also check the selfoilers on the system to make sure oil is being delivered where needed," Mr. Schreiner adds.
VMP expects it will have to add to its cleaning systems in the near future as production increases. "We will probably outgrow this system in 5 years, but we will definitely go back to Magnus for a larger system," says Mr. Schreiner.
The development of environmentally safe, yet effective solvents has kept vapor degreasing at the forefront of cleaning operations for metalworking.
A shop should look at all aspects of the production process to maximize productivity. This includes selecting an efficient cleaning system.
Parts cleaning, like most metalworking processes, is experiencing ever tightening specifications. Shops must continuously evaluate whether to clean parts in-house or use a supplier. This article looks at current aqueous cleaning processes and suggests criteria for the make or buy decision.