Ford investigating use of MuCell microcellular foam injection molding to reduce vehicle component weight
23 March 2011
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| Schematic of MuCell injection molding process (injection molding of microcellular plastics with characteristic microstructures). Kramschuster et al. 2005. Click to enlarge. |
Ford researchers have been investigating the use of the MuCell microcellular foam injection molding process to reduce component weight; weight reduction is a key Ford strategy to help lower fuel consumption. (Earlier post.)
MuCell, developed and patented by MIT and now owned by Trexel Inc., involves the highly controlled use of a gas such as CO2 or nitrogen in its supercritical state (SCF) in the injection molding process to create millions of micron-sized voids or bubbles in uniform configurations. The voids are created as a result of homogeneous nucleation that occurs when a single-phase solution of polymer and gas passes through the injection gate into the mold.
The single-phase solution is created through the operation of a conventional injection molding machine which has been modified to allow the creation of a single-phase solution. Trexel says that the key modifications to the system involve the use of a precision SCF delivery system to deliver SCF to special injectors based on mass flow metering principles.
The SCF is then injected into the barrel where it is mixed with the polymer via a specially designed screw. A shut-off nozzle maintains the single phase solution while the injection molding screw maintains sufficient back pressure at all times to prevent premature foaming or the loss of pressure which would allow the single phase solution to return to the two phase solution.
In Ford research trials, the microscopic bubbles reduced component weight up to 10%, while retaining all necessary properties for a non-visible part and without sacrificing dimensional integrity or durability.
Using MuCell technology also eliminates pack and hold times in the molding/cooling process (to address warpage), reducing cycle times. With MuCell, the typical time to mold a part during trials ranged from 30 to 60 seconds, a 50% time improvement.
The MuCell process also requires less clamping force, allowing a reduction in injection press size by up to 50%; reduced cycle times and clamping forces translate to energy savings and reduced CO2 emissions associated with production.
Ford says that it is continuing to research potential uses of MuCell technology for production of interior components. Ford also has patents pending on improvements to the MuCell process.
Resources
Adam Kramschuster, Ryan Cavitt, Donald Ermer, Zhongbao Chen, Lih-Sheng Turng (2005) Quantitative Study of Shrinkage and Warpage Behavior for Microcellular and Conventional Injection Molding. Polymer Engineering and Science. doi: 10.1002/pen.20410
L. J. Hyde, L. A. Kishbaugh and J. A. Katterman (2002) How Microcellular Foam Molding Changes the Cost Structure of Injection Molded Automotive Components: A Review of the Process and Automotive Applications (SAE 2002-01-0717)
Jingyi Xu and David Pierick (Trexel) Microcellular Foam Processing in Reciprocating-Screw Injection Molding Machines
To me, this seems like a waste, with relatively insignificant benefits. If people & the belongings they'd have in their vehicles was constant, I'd say this is great...but because of the variability in the shapes and sizes of people & the stuff they are going to have in their cars on a regular basis, I can't see how this makes a difference in the long run. The 500 lb gorilla in the room is the vehicle engine, vehicle frame & drive train, including axles & wheel hubs. It's like telling obese people we're going to focus on giving them the most technologically advanced haircuts to help them with their weight issues...does that make any sense?
Posted by: ejj | 23 March 2011 at 06:47 AM
Every pound is important including the extra 100+ lbs behind the wheel and for people in the other seats. Very few private cars need to weight more than 2000 lbs. As for driver/passengers mass, restricting junk food may help to keep their weight down. Maybe, obese people should drive trucks or vehicles specially made for them. Why should normal weight people pay more for over designed over weight vehicles.
The latest news is that coloring in Colas increases cancer growth and we all know that all Colas help people to gain weight.
Posted by: HarveyD | 23 March 2011 at 07:17 AM
The idea is strong enough and light enough at a low cost. Pontiac and Saturn both used space frames and polymer panels to reduce weight. They may have been ahead of their time, but perhaps the situation may start to catch up to itself.
Posted by: SJC | 23 March 2011 at 07:49 AM
ejj,
It's hard to force ourselves to the discipline, but there rarely is some "magic bullet" that gets the weight down.
One of my mentors when we were doing some early projects to reduce weight on some military applications told me to stop looking for that one magic bullet "weight reduction comes from hundreds of little fixes all over the project".
These steps are important.
Posted by: DaveD | 23 March 2011 at 10:56 AM
@ejj,
All other things being equal you are right, but all other things don't have to be equal is precisely the point.
IFF you can lower the weight of the frame, the panels, the seats, the chassis, etc. then you can lower the power, and hence weight, of the engine and drive train. The more thoroughly you do this, the more you get a virtuous feedback loop.
The process is limited because you still need enough power to allow for 5 occupants and some luggage, but if you can subtract 500-800 pounds from most vehicles, it makes a big difference across the whole fleet.
Posted by: HealthyBreeze | 23 March 2011 at 10:57 AM
I took the door panels off my truck a while back to apply sound deadening material...the black stuff with the adhesive on the back. The panels weigh about 10 lbs each? But they are not 100% foam...they're probably 50% pressed foam/fiberglass, 25% vinyl / polyester carpet, 25% plastic. So let's say this special foam is used on all the panels with a 50% weight savings & you get maybe 2-3 lbs savings per panel? * 4 = 12 lbs. Let's say add another 12 lbs for dashboard & seats, so you are saving ~25 lbs? Nothing special there. Now instead, if they used their research dollars to develop an economical ultra-lightweight & super strong replacement for steel, that is something that would be more impressive, since there are many more real, significant potential savings in replacing steel vs. foam.
Posted by: ejj | 23 March 2011 at 11:32 AM
What would be really clever would be to make the material act as a capacitor
Posted by: 3PeaceSweet | 23 March 2011 at 12:19 PM
That would be cool, you drive your super cap :)
Posted by: SJC | 23 March 2011 at 12:55 PM
A 300-ton aircraft can carry up to 100-ton of cargo.
A 600-lbs vehicle should be able to transport at least one or tow 200-lbs users?
Posted by: HarveyD | 24 March 2011 at 10:43 AM