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Big Plastic Parts-Part 2: Using Substitute Processes May Put Money in the Bank!

Big Plastic Parts Manufacturing

Choices Dictated by Capability

For decades, certain processes were used to make certain classifications of molded parts.  Limitations in the processes, part size, complexity and overall requirements became the gates that specified the techniques.  Unfortunately, some of these processes were slow, had high scrap yield, and even higher piece costs.  Environmental issues also existed, but, the processes at least yielded something serviceable. 


Time to Pipe Up!

A classic example was in the development of the valve stacks for some of the heavy process control piping systems-frequently seen in the chemical and mining world.  The requirement was for durable, high volume valves to handle frequently corrosive liquids, slurries and powders.  Having seen what chemical industry material flow can do to conveying/piping systems, the limitation are pretty quickly evident. 


In one case, powdered basalt mineral was piped through a conveying system, including glass lined, stainless steel elbows.  The elbows lasted exactly 45 minutes before falling apart.


Where Have These Part Ended Up?

Actually, Utah.  The current process uses a unique approach known as bulk injection molding.  EnviroTech Molded Products, Inc. of Salt Lake City, UT has developed a method for injection molding large piece weight, thick parts.  Maximum capacities hit 530 lb. and 5” thick!


In the case of high wear and corrosion resistant valves, EnviroTech tooled and produced a valve body weighing 91 lb. (200.2 kg), with a wall thickness of 4.5 in (11.4 cm).  The material selected was a high lubricity, tough, engineering resin, and superior in wear and corrosion resistance.  A real difference comes in the form of the predecessor part required a steel casting or fabricated fitting, with a ton of secondary operations and subject to casting and machining defects.  The tooled, molded part was highly reproducible, and required less production time-all for a lower cost.




·         Large parts: from 2 oz. to 530 lb.

·         Heavy wall sections: up to 5" thick

·         Complex configurations: Varying cross sections, openings, and internal ribs

·         Low cost tooling: Design, material and manufacture

·         Economical production runs: 50 to 50,000 pieces per year

·         Lightweight parts: 80% lighter than most metals

·         Corrosion resistance: Plastics can operate in severe chemical environments

·         Abrasion resistance: Plastics offer superior abrasion resistance

·         Materials expertise: Over 46 years of molding experience

·         Single-source responsibility: From part design through finished product


What Else Has Been Substituted?

Another area which has been substituted is the labor-intensive world of fabricated parts.  Whether wood or metal, numerous parts needed to be fabricated for use as structural panels or dunnage.  While the person-hours to make the parts can be costly, the training and skill levels of those operators required a higher degree of attention to detail.


One highly saleable approach is the use of thermoforming or pressure forming.  With the capability of making reproducible, volumetric parts as large as large as 5’ x 10’ x 4.5’, gone is the necessity for handmade fabrication, except in the cases of one off or prototype applications.  Couple that with the ability to supply secondary machining (piercing, routing, sawing and milling), the parts can be painted and decorated to render them suitable to various applications.  Milwaukee’s own General Plastics, Inc. specializes in large thermoformed parts for both the OEM and POP industries.


Take advantage of JIT, kanban, drop shipment, rush order and other customized delivery requests to smooth out your supply chain needs.


Contact the staff at Todd & Associates, Inc to explore the capabilities of these companies in your process.  And remember-there are clearly may be more processes to achieve your molding goals!