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Sajar Plastics History and Description

History of Sajar Plastics

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Sajar Plastics was founded in Middlefield, Ohio in 1949 with three plastic injection molding machines producing straight injection molded parts. “Sajar” is an acronym reflecting the last names of the founding three owners of the company. Sajar grew steadily over the years expanding manufacturing capabilities and facility to over 150,000 sq. ft., a direct result of earning a reputation in the custom molding industry as an innovative molder supplying high quality large plastic parts with complex designs and high cosmetic requirements at competitive prices.

In the early 1980’s Sajar was one of the three original companies which developed gas assisted injection molding and continues to pioneer its use and application today. Since then Sajar has acquired the equipment and processing technology necessary for the production of large complexly designed parts and the quality culture required to produce consistent high quality cosmetics on customer facing components. To date Sajar has commercialized over 500 gas assisted parts for leading OEMs in a wide variety of industries including medical, laboratory and diagnostic, manufacturing, business, and retail registers/dispensing machines.

With small, medium, and large tonnage presses, along with in-house painting and full secondary operations and assembly, Sajar is well equipped to consolidate your supplier base by acting as a one stop shop for large projects requiring a wide variety or plastic part sizes and finishing specifications. We welcome your visit so you can see our gas assist technology and capabilities.

World Leader in Large, Highly Cosmetic Plastic Parts

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Internal gas assist injection molding is a low pressure process requiring the introduction of a short shot of molten resin into the mold which is immediately followed by the injection of high pressure nitrogen gas. The gas flows through strategically located gas channels by displacing the molten resin in the channel interior, thereby forming hollow sections.

The pressurized gas pushes the molten resin tight against the cavity walls until the part solidifies, and the constant, evenly transmitted gas pressure keeps the part from shrinking and warping while also reducing surface blemishes, sink marks, and internal stresses. This process produces a large plastic part with superior surface aesthetics and tight dimensional control over large distances.

In external gas assist injection molding the molten resin is introduced into the mold but the gas is injected in a micro-thin layer between the back surface of the part and the mold core, thereby forcing the front surface of the part against the opposite side of the mold cavity. As the resin cools the pressurized gas guarantees the front side of the part precisely replicates the surface of the mold.

This process is best for high profile and large surface area plastic parts, especially those requiring detailed textures and superior surface aesthetics. Warp and sink marks are eliminated because the gas packs out the resin as it solidifies. As with internal gas assist, support ribs and bosses can be molded into the part yielding similar dimensional stability and tight tolerances. Molding pressures are also likewise reduced generating less residual stress on parts and wear on molds.

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