Outcome

How Injection Molding Works

http://www.cs.cmu.edu/~rapidproto/students.03/mrau/project2/report/1.html  

http://www.custompartnet.com/wu/InjectionMolding

The plastic injection molding process produces large numbers of parts of high quality with great accuracy, very quickly.

Plastic material in the form of granules is melted until soft enough to be injected under pressure to fill a mold. The result is that the shape is exactly copied. Once the plastic molding has cooled sufficiently to harden, the mold opens, releasing the part. The whole injection molding process then repeats.

CLAMPING:

The moving and fixed plates of the injection molding machine hold the mold tool together under pressure.

INJECTION

The molten plastic that has been melted from its pellet form in the barrel of the molding machine is injected under pressure into the mold.

DWELLING

After the molten plastic has been injected into the mold, pressure is applied to ensure that all cavities are filled.

COOLING

The plastic parts are then allowed to solidify in the mold.

OPENING

The moving plate moves away from the fixed plate, separating the mold tool.

EJECTION

Ejection of the completed plastic molding from the tool is aided by use of rods, a plate, or air blasts.

-- http://www.rutlandplastics.co.uk/advice/moulding_process.html

Uses of Injection Molding

This process can be used to mold with a variety of materials, especially thermoplastics.

The primary use of injection molding is to create a lot of simple pieces of material such as bottle caps or LEGO pieces.  It is one of the most cost efficient processes of manufacturing.

Limitations of Injection Molding

Cost of Injection Molding

The cost of manufacturing injection molds depends on a very large set of factors ranging from number of cavities, size of the parts (and therefore the mold), complexity of the pieces, expected tool longevity, surface finishes and many others. The initial cost is great, however the piece part cost is low, so with greater quantities the overall price decreases. With global competition, companies with an ISO-Quality system usually will have better pricing as they have streamed lined their process and produce less defects. 

-- https://www.xcentricmold.com/about-injection-molding.php

Locations in CMU

"The injection mold machine is in the Rothfus Lab run by Matt Cline in the Chemical Engineering Department."  - Lawrence M. Hayhurst

The Rothfus Lab can be accessed through Doherty Hall A100.

How to Access Locations in CMU

As long as you have the mold and the plastic, the machine may be used on Mondays, Tuesdays, and Thursdays from 12:30-3:30 PM.  It is also possible to access it in the Mornings of Mondays and Fridays.

Matt Cline suggests reading the manual, watching a 10 minute video, and spending 10 minutes with him for first time users.  It is also suggested that you arrange to have the machine heated up two hours before arrival and then spend two hours purging the unit of excess plastic.