New adventures in Part Designing
The recent International Plastics Design Competition, held during NPE2012, turned a spotlight on some of the most innovative new part designs on the planet. Here's a look at those that used engineering resins - including a couple of award winners.
June 1, 2012 by Canadian Plastics
Pneumatic tube carrier makes hospital life easier
WHAT: A new medical grade carrier assembly has been designed to lift the workload of hospital staff that use these carriers every day in the course of caring for patients. To be an improvement, the carrier had to fit all of the mechanical specifications required by a multitude of installed tube systems, handle the same payload as any current carrier, and be even easier to use.
HOW: Molded and assembled in the U.S. from 10 injection molded parts, the new carrier is lightweight, with an ergonomic exterior design that allows for easy and secure holding and operation. The exterior shape allows the carrier to be used in all existing hospital tube systems, including older systems with 36-inch tube bend radii — current competitive carriers are made for the more modern systems with 48-inch tube bend radii.
The end design of the carrier acts as a convenient grab feature as well as providing a stable base when standing the carrier on end. In addition, the design of the carrier end incorporates interchangeable end bumper inserts to provide protection for the carrier during use in the tube system.
The twin rotatable latches provide secure closure and intuitive user-friendly operation, including visual, audible, and tactile feedback designed to provide the user with either a “Ready to Send” or a “Caution” indication.
For the main container housings, a bisphenol A(BPA)-free PET copolymer was chosen for superior impact resistance, chemical resistance, and clarity, as one-half of the housing remains clear so the user can see the contents and inspect for leakage prior to actuating the latches to open the carrier.
DESIGNER: MacLean-Blevins & Associates, Inc.
MATERIALS: Eastman Chemical Company
MOLDER: Seitz Corporation
WINNER! Best in Show, Buildings & Furnishings and Sustainable Consumer Product awards
WHAT: An exact replica of the iconic 1940’s aluminum chair designed for the U.S. Navy, the 111 Navy Chair is molded from approximately 111 recycled soda bottles per chair.
HOW: This one was tricky from the get-go: since there were no computer-aided design files in existence — or even any surviving prints of the original chair — reverse engineering was necessary to duplicate the shape.
The new chair is molded in a single cavity using gas-assist technology to optimize cycle time and reduce overall chair weight. Extensive use of mold filling analysis was utilized to confirm knit line locations, minimize warpage, and prevent gas traps. High-end gas-assist simulation software confirmed gas penetration and optimized the injection molding cycle times. Non-linear finite element analysis was used in the design phase to confirm the chair’s structural integrity.
Innovative robotic automation was also used extensively. A six-axis robot demolds the chair and positions it for automatic degating and subsequent assembly. The chair’s structural H-brace, made from recycled PET, is press-fit into place, requiring no additional fasteners. With only four screws to remove, the chair can be easily prepared for end-of-use recycling. The chair is available in six colors: red, snow, flint, grass, persimmon, and charcoal. Each color is made from a paint-free molded-in color process.
MATERIALS: BASF Corporation
MOLDER: To Be Determined
Nothing runs like a polycarbonate Deere
WHAT: Right and left hand tractor panels designed for John Deere’s 6.8 litre and 9.0 litre engine tractors. The fixed panel uses temperature-resistant polycarbonate, eliminating the need for a sheet metal cover close to the engine compartment, maximizing cooling while keeping out chaff and debris.
HOW: There are four part numbers in this family. The largest panel is 197 cubic inches, and all four part numbers come from one mold running in a 3,000 tonne press. Due to material characteristics, molder Innovative Injection Technologies (i2tech) runs one cavity at a time, using the same manifold; they flip the manifold and switch from one cavity to the other, eliminating the need for another mold. When switching panels for the larger tractor, they also switch inserts.
Cosmetically, the part was designed with a new texture to match the painted surfaces adjacent on the tractor. Working closely with Deere & Company, i2tech developed a specific texture to mimic the appearance of orange peel on a painted part.
The biggest obstacle? Maintaining a consistent depth on large parts. “The total material removal and actual texture depth are so slight that any deviation in the etching process would completely destroy the look, resulting in a tool that would need to be completely polished and retextured,” i2tech said. “Also, in order to maintain an ‘orange peel’ look, the tooling has to be polished to an SPI-A1 finish after texture. This was done in the texture house to ensure the texture wasn’t removed in the process.”
DESIGNER: Deere & Company
MATERIALS: SABIC Innovative Plastics
MOLDER: Innovative Injection Technologies (i2tech)
WINNER! People’s Choice Award
Injury-Free way to take the zest out of citrus fruit
WHAT: In case you didn’t know, so-called spin zesters are designed to safely and easily remove the desired “zest” from citrus fruits, minus the pits. (Traditional zest removal involves holding the fruit in one hand while managing a sharp knife with the other — not exactly the safest method.) Called the Zip Zester, this particular spin zester is designed to control the orientation of the fruit to the rasp while simultaneously removing your hands from the cutting area.
HOW: Made of a composite base, a variable tension spring arm, and an over-molded micro-etched stainless steel screen. The composite base is a one-piece molding of 60 per cent glass-filled polyamide, achieved through a complex mold consisting of multiple slides and lift cores.
The arm is molded out of Delrin 100, a material chosen for its flexural fatigue properties. The design has a curved, tapered beam that serves as an integral spring. The stainless steel screen is photo-etched to create the blade tines in the flat blade form.
The blade injection mold was designed to simultaneously over-mold the screen while bending the tines into position to serves as blades, thereby eliminating the blade formation as a secondary operation. The formed screens are inserted into a slot with 0.001-inch tolerance just prior to injection. The over-mold material is 50 per cent glass-filled polyamide.
All parts were designed using SolidWorks Premium CAD software. The entire assembly was designed with snap-fits to eliminate assembly tools. Initial prototypes were 3D printed, and final functional prototypes were produced in glass-filled nylon using the SLS (selective laser sintering) process.
DESIGNER: GrassRoots Industries
MATERIALS: EMS-Grivory, DuPont
MOLDER: Cashmere Molding Inc.
Contamination-proof sports beverage cap
WHAT: The “Evolution” sports cap for beverage containers, designed to provide sustainability, functionality, and to be contamination-proof for aseptic filling.
HOW: The closure — which looks like a three-part assembly but is actually a two-part assembly — is molded on a two-component machine, and can be made of either HDPE or polypropylene. The polypropylene version can be made of a tinted transparent material, opening up possibilities for having a colored spout on the inside to differentiate plain and flavored waters or for different versions of so-called smart drinks.
The second part of the body is the over-molded “flip top tab”, made of a 100 per cent FDA-approved TPE which gives the hinge a 180-degree flex. The plug seal is integrated into the body of the closure to form the bore seal, and the TPE covers the top and forms the hinge area.
The spout of the closure is made of HDPE as a single piece and is then assembled into the body; it can be made with either round or oval openings to further enhance drinkability.
There are no loose pieces to cover the drinking surface, unlike on clear “dust caps” found in traditional push-pull closures; there are also no holes or recesses in the closure, which keeps out dirt or dust.
Finally, since tamper evidence was critical in this application, the Evolution has three thin sections of the closure body which provide the visual evidence of tampering — when the closure is opened, the thin section is visibly torn in the three areas.
DESIGNER: DPI International
MATERIALS: To Be Determined
MOLDER: To Be Determined