This topic contains a solution. Click here to go to the answer

Author Question: If non-melted resin particles are noted in the molded part what corrections might be made? What ... (Read 156 times)

kfurse

  • Hero Member
  • *****
  • Posts: 590
If non-melted resin particles are noted in the molded part what corrections might be made?
 
  What will be an ideal response?

Question 2

Why is it important to have the sections of the molded part as uniform in thickness as possible?
 
  What will be an ideal response?

Question 3

What is packing the mold and why is it important in obtaining good injection molded parts?
 
  What will be an ideal response?



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
Marked as best answer by a Subject Expert

trampas

  • Sr. Member
  • ****
  • Posts: 320
Answer to Question 1

The first step in solving the problem would be to investigate the heating. Are the temperatures too low for this resin or are there cold spots where the heaters are not operating properly? Is the polymer being mixed homogeneously or are dead spots occurring? Is there a combination of effects of heating and mixing? Lastly, is the feed homogeneous? The presence of large and small particles in the feed will complicate the melting process because the large particles take more time and energy to melt than so the small particles. This last problem may require some separation of the particles or a homogenizing step such as re-extrusion.

Answer to Question 2

Thick sections cool more slowly than thin sections because of the time required for the heat to move through the plastic material. The cooling occurs from the outside toward the middle because the heat is transferred most easily from the outside. Therefore, the inside is liquid after the outside is solid. Because of the natural shrinkage that occurs upon cooling, the liquid can still shrink whereas the outside, which is solid, cannot. This may cause a sink mark over the center

section as it cools and shrinks. This problem can be solved by making all the sections of the same thickness.

Answer to Question 3

Packing is the process of continuing to inject resin into the cavity even after the cavity is full. As the plastic shrinks from thermal processes




trampas

  • Sr. Member
  • ****
  • Posts: 320

 

Did you know?

Signs and symptoms that may signify an eye tumor include general blurred vision, bulging eye(s), double vision, a sensation of a foreign body in the eye(s), iris defects, limited ability to move the eyelid(s), limited ability to move the eye(s), pain or discomfort in or around the eyes or eyelids, red or pink eyes, white or cloud spots on the eye(s), colored spots on the eyelid(s), swelling around the eyes, swollen eyelid(s), and general vision loss.

Did you know?

Inotropic therapy does not have a role in the treatment of most heart failure patients. These drugs can make patients feel and function better but usually do not lengthen the predicted length of their lives.

Did you know?

The term bacteria was devised in the 19th century by German biologist Ferdinand Cohn. He based it on the Greek word "bakterion" meaning a small rod or staff. Cohn is considered to be the father of modern bacteriology.

Did you know?

Anti-aging claims should not ever be believed. There is no supplement, medication, or any other substance that has been proven to slow or stop the aging process.

Did you know?

More than nineteen million Americans carry the factor V gene that causes blood clots, pulmonary embolism, and heart disease.

For a complete list of videos, visit our video library