Powder injection molding yields new control technology.
Injection molding injection molding
A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold. of metal or ceramic powder with a thermoplastic A polymer material that turns to liquid when heated and becomes solid when cooled. There are more than 40 types of thermoplastics, including acrylic, polypropylene, polycarbonate and polyethylene. binder is the province of a small number of firms that have mastered the specialized processing know-how and expensive post-molding techniques. While definitely not for everyone, powder injection molding (PIM (1) (Protocol Independent Multicast) A multicast routing protocol endorsed by the IETF. Used in conjunction with an existing unicast routing protocol, it comes in two flavors: Dense Mode (PIM-DM) is used when recipients in the target group are in a concentrated ) has generated some interesting new control technology that could benefit other types of injection molding. That fact emerged during the annual PIM Symposium held recently in State College, Pa., by the Metal Powder Industry Federation of Princeton, N.J.
HIGH-SPEED INJECTION CONTROL
One area in which PIM processing shares concerns common to other precision molding applications is in controls technology. As explained by Dr. Karl Hens, program director of the PIM Consortium at Penn State University in University Park, PIM often requires fill rates as fast as 0.12 sec in order to counteract the high thermal conductivity of metal-powder compounds, which promotes fast cooling. Such fast injection in turn requires some novel control techniques. In Penn State's PIM laboratory, a specialized Engel machine with a RISC-based CC100 controller and robust sensing capabilities does the trick. For each shot, Hens says, this "advanced control with in-situ correction" uses both cavity-pressure - from piezo-electric sensors - and temperature measurements to determine the optimum transfer pressure at which to switch from speed to pressure control. (See PT, Aug. '94, p. 15 for an earlier report on this development program.)
Recently emerging from the lab, this control technology has been incorporated in a commercial system from Kistler Instrument Corp., Amherst, N.Y. Kistler's Automatic Quality Control System (AQCS AQCS Analytical Quality Control Services
AQCS Air Quality Compliance Solutions (California) ) automatically determines the optimum transfer pressures needed to get a good packing-pressure profile. The system identifies the end of volumetric volumetric /vol·u·met·ric/ (vol?u-met´rik) pertaining to or accompanied by measurement in volumes.
Of or relating to measurement by volume. filling by a sharp upward bend in the cavity-pressure signal. AQCS monitors material viscosity during cavity filling and applies this data to the transfer-pressure calculations. Kistler maintains that mathematical methods alone won't yield the optimum transfer pressure in real time, so it also incorporates some "fuzzy-logic" decision making into its automatic calculations.
From shot to shot, AQCS will choose different transfer pressure points because of variations in feedstock feed·stock
Raw material required for an industrial process.
Noun 1. feedstock - the raw material that is required for some industrial process
raw material, staple - material suitable for manufacture or use or finishing viscosity, but the AQCS will hold a consistent maximum cavity pressure. Kistler product manager Karl Bauer says that AQCS works on the principle that "consistent maximum cavity pressure is equivalent to consistent part quality." In the case of thick-wall parts, the system shoots for a cavity-pressure integral, rather than a maximum cavity pressure. But otherwise the control works the same way.
At the symposium, Bauer announced that the AQCS cavity-pressure control system will soon be embodied in a computer chip that can be installed in a variety of OEM (Original Equipment Manufacturer) The rebranding of equipment and selling it. The term initially referred to the company that made the products (the "original" manufacturer), but eventually became widely used to refer to the organization that buys the products and controllers - thanks to EuroMAP integration standards. The chip's official introduction will be at the upcoming K'95 show in Dusseldorf, Germany.
NEW PIM MATERIALS
BASF BASF Bar Association of San Francisco (since 1872; San Francisco, California)
BASF Badische Anilin und Soda Fabrik (German chemical products company)
BASF Builders Association of South Florida Corp. of Wyandotte, Mich., now offers ready-to-mold PIM feedstocks combining various metals and ceramics with an acetal acetal /ac·e·tal/ (as´e-t'l)
1. any of a class of organic compounds formed by combination of an aldehyde molecule and two alcohol molecules.
2. resin binder. Besides eliminating the need for molders to compound their own feedstocks, BASF also provides engineering support for processors who know injection molding but lack expertise in debinding and sintering sintering, process of forming objects from a metal powder by heating the powder at a temperature below its melting point. In the production of small metal objects it is often not practical to cast them. . "We provide help all along the process - from the molding to the sintering," says David Krueger, who works on PIM applications for BASF.
According to according to
1. As stated or indicated by; on the authority of: according to historians.
2. In keeping with: according to instructions.
3. BASF's Dr. Jan Ebenhoch, the use of acetal has several advantages over the conventional wax/polyolefin binders: Acetal gives the molded parts enough strength to withstand automatic handling. As an engineering resin, it fosters tighter tolerances than the wax binders. And acetal debinding can be accomplished through a catalytic process that is easier to control and up to 10 times faster than thermal debinding, depending on part geometry and powder particle size Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. . The acetal binder also complements BASF's developmental reactive sintering method, in which sintering in a hydrogen atmosphere yields low-carbon stainless steels stainless steel: see steel.
Any of a family of alloy steels usually containing 10–30% chromium. The presence of chromium, together with low carbon content, gives remarkable resistance to corrosion and heat. .
PIM PROCESSING TIPS
A wear-resistant injection barrel and screw are the most obvious requirements for PIM, but speakers at the symposium pointed out several other technical considerations that should be considered by anyone exploring this field.
* Screws: Torsten Kruse, technical training engineer for Arburg Inc., Newington, Conn., notes that screws do not need a compression section because the highly filled PIM feedstocks don't compress. Arburg sells complete systems for PIM, adding the requisite pre-mold and post-molding equipment to its standard AllRounder machines.
* Gating: "End users want a tiny gate," notes Dr. Hens, but PIM parts are likely to require larger gates than normal plastic parts. The guideline, he says, should be to avoid separation of powder from polymer binder, which means keeping shear rates below 10,000 [sec.sup.-1].
* Hot runners: "You don't have to rush the filling as much when you use hot runners," says Hens, because hot runners get the feedstock to the mold hot enough to forestall fore·stall
tr.v. fore·stalled, fore·stall·ing, fore·stalls
1. To delay, hinder, or prevent by taking precautionary measures beforehand. See Synonyms at prevent.
2. premature solidification. Hens recommends only cylindrical hot-runner channels, which have a smaller surface area than trapezoidal channels of equal volume, resulting in less heat loss.
RELATED ARTICLE: PIM in Hot-Runner Parts
Metal-powder injection molding is starting to turn up in components of injection molding systems. At K'95 in Dusseldorf, Mold-Masters Ltd., Georgetown, Ont., will introduce powder-injection-molded hot-runner nozzles that will become part of the company's standard Dura Dura, in the Bible
Dura, in the Bible, plain, near Babylon, where Nebuchadnezzar set up a golden image.
Dura, ancient city, Syria
Dura (d series. Mold-Masters, which also offers other hot-runner systems for PIM, is molding these new components in-house on a machine from Engel Canada Ltd., Guelph, Ont. According to Mold-Masters R&D director Hakim Belhadjhamida, PIM allows the nozzles to be better optimized for high-wear applications.