How to demold parts faster, with less stress & surface defects.* You may need to unlearn what you always thought was the right way to get parts out of an injection mold. You will have to reprogram re·pro·gram
tr.v. re·pro·grammed or re·pro·gramed, re·pro·gram·ming or re·pro·gram·ing, re·pro·grams
To program again.
re the sequence of steps for mold opening and ejection ejection /ejec·tion/ (e-jek´shun)
1. the act of casting out or the state of being cast out, as of excretions, secretions, or other bodily fluids.
2. something cast out.
3. . But if you are making deep cup-shaped or box-shaped parts with little or no draft, especially ones with external undercuts or surface texture, the benefits of rethinking the demolding steps can be faster cycles and fewer rejects due to distorted, scratched, or marred products.
Paul E. Allen, president of Logic Corp., a supplier of mold-temperature controllers, cluster valves, and manifolds This is a list of particular manifolds, by Wikipedia page. See also list of geometric topology topics. For categorical listings see and its subcategories. Generic families of manifolds
Incremental cost is additional or increased cost of an item or service apart from its actual cost. Cavity Extraction (I.C.E.). It uses the material shrinkage to help, rather than hinder, ejection of difficult parts.
Typically during molding the part shrinks around the core. The part is separated from the core using ejectors, air, and/or a stripper Stripper
Slang for an individual homeowner who strips the equity out of his or her home through mortgage refinancing. Proceeds are generally not re-invested, but spent on consumer goods.
Most people get rich by saving and investing wisely. plate. However, if the part has shrunk too tightly onto the core, a number of potential part-removal problems can loom, says Allen.
"The core restricts the free shrinkage of the part, so stresses are created," he explains. In addition, high ejection or stripping forces may be required to push a cooled part off the core, and these forces can deform or wrinkle Wrinkle
A feature of a new product or security intended to entice a buyer. the part or impart added stresses.
At the same time, an undercut or textured exterior surface can make the parts difficult to remove from the cavity without deforming or marring the show surface of the part. Again, this occurs because the core restricts the ability of the part to shrink away from the cavity surface. The difficulties are magnified when parts have very low draft angles.
Up to now, solutions to these difficulties have included compromising part design to add more draft or using mold releases, slides in the tool, or highly polished molds--all of which add cost.
Simultaneous mold actions
Logic's I.C.E. process allows the molten plastic to relieve stresses in the mold while also reducing ejection force requirements. In some cases, air ejection may be adequate without ejector ejector
n by common usage, a device used to remove debris and fluids by negative pressure. Another term is
aspirator. See also aspirator. pins or a stripper plate.
The first goal of I.C.E. is to break the tight adhesion of the cooling and shrinking part to the mold core. The second goal is to allow the part to shrink radially away from the cavity wall cavity wall
In architecture, a double wall consisting of two wythes (vertical layers) of masonry separated by an air space and joined together by metal ties. The cavity allows moisture that penetrates the exterior wythe to drain. . Both are achieved by partially withdrawing the core from the part while the part remains in the cavity.
When the core is partially retracted re·tract
v. re·tract·ed, re·tract·ing, re·tracts
1. To take back; disavow: refused to retract the statement.
2. the initial stresses building up between the still molten center of the part and the cooling skin are allowed to relieve themselves. "Cooling and shrinkage now occurs radially across the diameter of core, instead of just across the thickness of the part," says Allen. The mold then opens fully, withdrawing the part from the cavity and allowing complete ejection off the core.
To break the adhesion between the core and the part the I.C.E. process requires a small movement of the core without fully opening the mold. A modification of the normal sequence program for the injection machine will be required. The incremental ejection distance off the core varies depending on part shape and surface, and resin used. "Incremental ejection of the part off the core can be carried out over a distance as little as 0.010 in. It has to be sufficient to break the grip of the part on the core but maintains the part engaged on the core for full withdrawal," says Allen. "Movement of the core and ejector or stripper plate is controlled using linear transducers and optical comparators--standard equipment on injection presses."
At the same time, I.C.E. requires that the part does not move during the initial core movement. The part can be held in the cavity using ejectors, a stripper plate, shop air, or combinations of these. The most common approach is to use the stripper plate and ejector system. When core retraction In the law of Defamation, a formal recanting of the libelous or slanderous material.
Retraction is not a defense to defamation, but under certain circumstances, it is admissible in Mitigation of Damages. Cross-references
Libel and Slander. begins, the stripper plate or ejector system, which operates independent of the core movement, is moved forward at the same time and same speed as the core retracts. The ejector movement holds the part against the cavity. Any molding machine (Woodworking) A planing machine for making moldings
(Founding) A machine to assist in making molds for castings.
See also: Molding Molding with true "eject-on-the-fly" capability can be utilized, says Allen.
Users can also employ shop air piped through the core to hold the part to the cavity while the core retracts. Logic has developed an auxiliary air-control device for this purpose.
This process requires that the moving and stationary mold halves be parallel. "You can mold parts with a zero draft angle, but the molds have to absolutely straight," Allen says. He prefers using the tiebars
and leader pins to keep the molds in line, instead of just cam locks.
A big benefit with I.C.E. is that parts can be ejected hotter because there is less danger of distortion. This can trim overall cycle time.
What a user says
Logic licenses the I.C.E. process, including know-how for determining when to activate core and ejector movements and/or the air system. The patent (U.S. #5,932,164) was issued Aug. 3, 1999. So far, only a small handful of companies have used I.C.E, including Tupperware's Hemingway, S.C., facility, and custom molders Whirley Industries of Warren, Pa., BPW BPW Business and Professional Women
BPW Board of Public Works
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BPW Best Photographer of the World
BPW Borland Pascal for Windows Plastics of Wilbraham, Mass., and Prototype & Plastic Mold Co., Inc., Middletown Conn.
Prototype & Plastic Mold, a $6-million/yr molder mold·er
v. mold·ered, mold·er·ing, mold·ers
To crumble to dust; disintegrate.
To cause to crumble. See Synonyms at decay. of parts for military, medical, and industrial applications, has used I.C.E to produce a military battery cell casing of polysulfone. The part measures around 6.5 x 3 in. x 6.5 in. deep with only 0.15[degrees] of draft. Initially, Prototype Plastics used a three-part mold with a split cavity. But demolding difficulties still generated up to 20% scrap parts.
Use of I.C.E with a stripper plate and 100-psi shop air allowed use of a standard two-part mold, which was 30% to 35% less expensive to build, says Bruce Silver, process engineer. Further cost savings came from using a lower level of polish and eliminating the use of a release agent on the core. Cycle time was trimmed by 33%, and because the part's internal stresses are relieved in the mold, a secondary annealing annealing (ənēl`ĭng), process in which glass, metals, and other materials are treated to render them less brittle and more workable. step could be eliminated, Silver says.
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Logic Corp., Sandy Hook Sandy Hook, low, sandy peninsula, NE N.J., projecting 5 mi (8 km) N toward New York and separating Sandy Hook Bay from the Atlantic Ocean. At the northern end is a Coast Guard station and the former Fort Hancock, which was built to protect New York harbor and was , Conn. (203) 426-6500 * PTDirect: 329TT