Injection Mold the Assembled Product--Not Just Its Parts

It may be the ultimate in process consolidation--fully assembled, articulating products, made of seven or more parts, drop out of a plastic injection mold completely assembled.

Fickenscher America's In-Mold Assembly™ process, executed on a Ferromatik Milacron K100S-3F injection molding machine, is more like magic than molding. In fact, believability has been a real hurdle for company President Don Birdsall and Marketing Vice President Mark Elder who consult about the process across the United States.

Nevertheless, after more than a year of market education, a couple of automotive companies have contracted with Fickenscher America to use In-Mold Assembly to improve quality and cut costs on a variety of parts. Other substantial projects are in the design phase, too, while the company completes its QS 9000 registration.

Technology Transplant
Fickenscher America is the creation of Richmond, Indiana's entrepreneurial Elder family, owners of a variety of businesses that already included conventional injection molding. Started in Richmond 1995, the injection molder currently has about 28 employees in a 97,000 square foot facility.

The company's In-Mold Assembly technology is essentially a 'clone' of that developed by Fickenscher & Co. GmbH. This German toolmaking firm is well known in Europe for decades of multi-shot molding expertise, and has patented many aspects of its tool design.

The Elder management team had learned about the introduction of the Germans' patented process at a 1992 plastics industry trade show in Germany, and assumed it would sweep into the United States in just months. Instead, a few companies in the United States tried unsuccessfully to replicate the German process with their own technology.

Not handicapped with a 'not-invented-here' attitude, the Elder business team approached Fickenscher & Co. GmbH for an exclusive license and the technical knowledge to produce and market in-mold assembled products--not mold tooling--outside Europe. "We took the opposite approach of most American companies, choosing to transplant the entire German process into our company, then work with Fickenscher as our technology partner and toolmaker," says Don Birdsall. "The German company also had such a good reputation in multi-shot molding in Europe that we felt it appropriate to adopt the name, too."

Fickenscher America made a large investment in its license with the German company to ensure full support for part/tool design and manufacture, process consulting, etc., says Birdsall. "We purchased a Ferromatik Milacron injection press that is identical to the 20 or so custom-built for Fickenscher & Co. GmbH," he explains. "We need to be able to speak a common language when discussing a process. Also, if the Germans build and run-off a tool for us, they can send us a data cartridge from their machine that we drop in ours, and the process is cloned."

Lower Part Cost

Mark Elder believes that In-Mold Assembly is one of the advanced manufacturing technologies that will enable developed countries like the United States to remain competitive and keep jobs, even while costs rise for energy, labor, and environmental regulations. The process is already well established in Europe, and is widely used in the automotive, toy, and electronics industries. "Toy figures with articulating arms, legs, and heads were the first products done with In-Mold Assembly," he explains. "Today, complex parts, such as locking electronic connectors, gear assemblies, and dashboard air vents, are made for such companies as Volkswagen, Mercedes Benz, Siemens, Braun; while toy companies, such as Lego and Playmobil, continue to use the process."

Manufacturing savings begin with the elimination of costs associated with post-mold assembly: work-in-process inventories, labor, floor space, fixtures, robotics, and storage. "Conventional processing often requires multiple injection presses and operators, not to mention the cost for tracking component inventories, etc.," says Elder.

"More important," says Birdsall, "is that higher quality can be achieved for a lower cost. Because you get an operable part out of the mold, you can check the entire assembly's quality at the machine. You don't have to wait a week to get a batch of components assembled. You detect non-conforming product immediately at the machine. Your cost of quality is lower because your jeopardy is only one piece. You are only one part away from solving the problem."

In-Mold Assembly also yields much higher part-to-part consistency in fit and performance. "Who has not had a dashboard air vent with vanes that would not hold position," he asks. "With In-Mold Assembly, you don't have the stack-up of error in component tolerances that leads to these loose fits. You can design-in the fit you want to give the right amount of friction. With all the components molded and assembled at the same time on one machine, in one mold you get the desired result with a high degree of consistency. Even the most sophisticated robotic assembly or costly machined joints cannot duplicate the consistency of In-Mold Assembly."

How it Works

In-Mold Assembly is a multi-shot injection molding process resembling progressive stamping, so a finished part is ejected with each machine cycle. The first shot produces a preform--the second (sometimes third or fourth), the finished product. To achieve this, the preform has to move to a new cavity after each shot.

All shots after the first use a mold geometry created partly by the mold walls and partly by the preform surface. Dissimilar materials with different melt temperatures ensure no bonding between successive shots. "This molding technique has quality built into it," says Birdsall. "If any shot is short, you find out right away, because the finished part won't articulate."

Single Machine Does the Work of Three

Despite all the mold action and extra resin processing required for In-Mold Assembly, there is virtually no cycle time penalty because the Ferromatik hydraulic machine has the power and control 'reserves' to handle many simultaneous operations, making the whole process simple and fast. Fickenscher's machine starts out as a model K100S-3F, meaning a full-hydraulic, 100-mt clamp with three injection units, two horizontal and one vertical, all capable of independent operation.

The K100 is ideally suited for multi-component molding with high-action tooling. Its accumulator-based hydraulic system provides high constant flow rates to support simultaneous operations in clamping, injection, and ejection. Its multiple injection units are individually selectable and controllable, eliminating the need for special operator training. "This machine is versatile, too, not just for In-Mold Assembly--it can do multi-shot or mono-layer molding, with rigid, flexible, or elastomeric materials," Birdsall says.

The base machine is customized around the demands of Fickenscher's tooling. It has exceptionally wide platens for its size, along with extensions of the tie bars, widened tie bar spacing and a proportionally controlled ejector stroke. This accommodates large tools.

A host of other features also relate to interfacing the machine with Fickenscher molds, such as a manually controlled double-core pull circuit that terminates at the moving platen with connections to the mold ejectors, and another CRT-controlled double core pull circuit with connections to Fickenscher's mold mechanism.

First In-mold Assembled Automotive Air Vents in North America

Fickenscher America has German-trained, award-winning product and tool design capability in-house, along with 3D CAD systems capable of outputs in a customer's required format.

This capability was used in Fickenscher America's initial contracts, producing the first in-mold assembled automotive air conditioning vents in North America. The part is created in a multi-cavity, hot-runner mold--itself a major technology advancement driven by Fickenscher America's Technical Director and auto industry veteran, Jack Elder. "The original design called for a snap-together part, with a housing that retained the vanes and snapped into a cosmetic housing," says Birdsall. "The new three-component molding will cost considerably less than the original part."

Another project in process at the company illustrates that cost reduction is not the only reason to use In-Mold Assembly. The part in question had a lid with living hinge that did not live long enough. Fickenscher America proposed a two component molding with a full mechanical hinge, plus position detents (a product improvement) to hold the lid. "In this case, the customer gets a superior part, at the same price," says Birdsall.

Elder says In-Mold Assembly adds a new dimension to product design. "We think this is an unprecedented opportunity for us to create the future of 'Design for Assembly' in the United States," he concludes.

Getting Started with In-mold Assembly

Mark Elder says those considering In-Mold Assembly should apply it to a product already in production. This serves two purposes. It provides a clear before and after comparison, and it ensures you always have a back-up source while getting your feet wet with the new technology.

A practical minimum for cost-justification is about 250,000 parts per year, although quality and other issues can drive this much lower. Elder says not to worry about a major re-design of a part. To date, Fickenscher America as never requested revisions in the show-surface of a part.

Your product must be able to satisfy performance and environmental requirements when produced with 'common' commodity and engineering thermoplastics. However, this range is quite wide. Rigid, flexible, and elastomeric materials can all be combined. For example, soft gaskets can be in-mold assembled on a part. Fickenscher America can provide background information on an extensive number of successful resin combinations.

Other advice for the beginner includes a caution that components that move relative to one another must be of materials with a melt temperature difference of at least 50°F. And, for practical purposes, parts should fit into an eight inch square when placed in the as-molded position. However, there is no theoretical size limit to what could be done.

Parts can use a maximum of four different materials or colors, although two and three are the most common. Finally, insert molding is not recommended due to the risk of mold damage.

Elder adds, "The risks are minimal with In-Mold Assembly. The rewards are higher quality, lower piece price, and the ability to do things in ways that offer a compelling advantage in the marketplace."

Home |  About Us |  Back To Technical Library |  Contact Us
Copyright © 1996-2010 All Rights Reserved.
General or Technical Questions? E-mail