HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Comments
View Comments: Newest First|Oldest First|Threaded View
Roy Glenn
User Rank
Iron
The molded part will provide the reasons for changes.
Roy Glenn   10/19/2011 8:42:33 AM
NO RATINGS

It often happens in a preliminary mold design meeting that a seasoned mold designer will propose changes to the part design that will improve its production and reduce the cost to produce it. Sometimes this will stimulate a request to detail the proposed changes. Unfortunately in a second meeting when the details of these proposed changes are reviewed the decision will often be to keep the part as originally designed. Then after the mold is in production and there are issues with molding the part, a decision to follow proposed changes is then mandated.

You can take a donkey to the pond, but you cannot force the donkey to drink.

Tim
User Rank
Platinum
Re: Concurrent engineering should be a corporate mandate
Tim   10/18/2011 8:37:38 PM
NO RATINGS
Total agreement that it is important for the design engineer to see the parts being produced.  Seeing first hand voids, sinks, and knit lines helps future desigsn.  Even if the mold maker can make a mold to produce parts, it is not always guaranteed that a processor can produce quality parts from that mold.  A good mold shop will no-quote a design rather than enter into a losing project.

JimT@Future-Product-Innovations
User Rank
Blogger
Concurrent engineering should be a corporate mandate
JimT@Future-Product-Innovations   10/18/2011 5:40:22 PM
NO RATINGS

Everything described as “Design Rules” in this article is important, but its only an introduction to part design. As design engineers gain experience, they gain a wealth of knowledge that makes them so much more valuable to their employers. An inter-related skill of part-designer and mold-cavity designer emerges. This skill is often learned, but not often taught. This article is a start in the right direction. When we were struggling through it, we called in “concurrent design”.

 

Flash-back 25+ years. When I designed my first plastic part as a CAD designer in the early 80’s I knew NOTHING about tool design.  Constant wall thickness?  Draft? Gate location-? (what’s a Gate?).  This is basic stuff, not taught to CAD jocks at the time.  Not to mention the “zillion” issues (knit lines, glass content, shrink, fill rates) pointed out by my associates at Phillips in Wisconsin.   When that first horrid little part design was reviewed by an experienced tool designer, egos were bruised, but greater knowledge ensued.

 

The interrelationship of part design with mold design should be a corporate mandate.  Any person who designs a CAD database ought to be the same person who sits in the tool design consult at the mold-maker’s office.  The concessions can be discussed on paper, before they’re locked in steel. Later, that same Jr. part designer needs to be assigned to review the tool design, to gain understanding from the mold-maker’s perspective. Subsequently, the same person should visit the tool shop, see the tool being built, see it assembled and finally; sampled at press-side.  There is no greater education in manufacturing than to take part design geometry the full course; from an awkward CAD concept to the smell of molten Polycarbonate in the pressroom: the proving ground.

Tim
User Rank
Platinum
Mold Design
Tim   10/17/2011 8:13:35 PM
NO RATINGS
These are great tools for plastic part designers.  Keeping the wall thickness as uniform as possible definitely helps in the final part quality.  Varaiations in wall thickness especially thick to thin to thick again open up the possibility of quality issues like sinks and voids the end of fill.

Greg Stirling
User Rank
Platinum
Why Mold Design Matters
Greg Stirling   10/17/2011 4:07:55 PM
NO RATINGS
In multi-cavity molds, it is always best to designate which cavity the part originated from on the part.  It is not safe to assume that all cavities produce the exact same part due to flow, pressure, temperature variation, etc...

Beth Stackpole
User Rank
Blogger
Simple rules, strong results
Beth Stackpole   10/17/2011 8:00:26 AM
NO RATINGS
Phillips' four simple rules gives engineers a lot to go on. Also, Doug's point about making tooling issues and mold design requirements part of the early development process is spot on and can help teams avoid a lot of the rework and time delays resulting from having to make after-the-fact design changes to accommodate tooling. A lot of the CAD/CAE vendors are beginning to address this issue with new modules and capabilities as part of their broader design tool suites.



Partner Zone
Latest Analysis
Conventional wisdom holds that MIT, Cal Tech, and Stanford are three of the country’s best undergraduate engineering schools. Unfortunately, when conventional wisdom visits the topic of best engineering schools, it too often leaves out some of the most distinguished programs that don’t happen to offer PhD-level degrees.
Sherlock Ohms highlights stories told by engineers who have used their deductive reasoning and technical prowess to troubleshoot and solve the most perplexing engineering mysteries.
Airbus Defence and Space has 3D printed titanium brackets for communications satellites. The redesigned, one-piece 3D-printed brackets have better thermal resistance than conventionally manufactured parts, can be produced faster, cost 20% less, and save about 1 kg of weight per satellite.
A group of researchers at the Seoul National University have discovered a way to take material from cigarette butts and turn it into a carbon-based material that’s ideal for storing energy and creating a powerful supercapacitor.
Hacking has a long history in the movies, beginning with Tron and War Games and continuing through The Girl with the Dragon Tattoo.
More:Blogs|News
Design News Webinar Series
9/10/2014 11:00 a.m. California / 2:00 p.m. New York
7/23/2014 11:00 a.m. California / 2:00 p.m. New York
7/17/2014 11:00 a.m. California / 2:00 p.m. New York
9/25/2014 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Sep 22 - 26, MCU Software Development – A Step-by-Step Guide (Using a Real Eval Board)
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Class: September 30 - October 2
Sponsored by Altera
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service