Part, Gate & Runner Analysis

Are Mold Flow's offerings the best bang for the buck in working with SolidWorks to give mold fill, gate and runner analysis issues clear results for improving the molded part and molding cycle times?

I just haven't used these tools before except for Mold Flow Express.

I compared the fill of a well known part in Express vs the full Mold Flow and found that though the cavity fill was nearly the same and proportional (% times to fill to certain points), the limited options inside of Express gave fill times that were twice what the actual full version of Mold Flow gave.

I don't have any experience with any other similar applications.

Bo

The tools are just analysis tools, they don't really help improve cycle times. What they do is give you information which allows you to make better decisions if you know how to interpret the results.

The analysis is fairly accurate if you know how to set up the problems correctly. Same as FEA, GIGO. Fortunately with Moldflow, it's pretty easy, still there are things like mold temps and pressures and balanced cavities and hot runner systems that the average plastic part designer isn't going to know much about.

To get the most benefit from the tools it takes a mold set-up guy's hands on knowledge of the process and materials.

MF Express only does a single cavity part, single gate, and doesn't give you control over the runner/gate configuration (size, shape, length of runner). I wouldn't use it for gospel fill times, I would mainly use it to see if I could spot knit lines or air traps, and even then, you would want confirmation from a mold designer that you're putting the gate in the right location.

Moldflow is a very cool tool, but you need to consider more than what Express allows you to look at, and you need to have expertise to know how to set up and interpret the results.

As far as being worth the money, you'd have to be doing a fair amount of it for it to pay off, unless you have problems with scrapping/reworking a lot of molds. I think the companies which get the high end stuff are typically big shops that do a lot of parts and have in-house expertise. I know Rubbermaid uses it, and its the mold engineers who do it, not the part designers.

There's not much to compare it to either. There was some software that came from Asia that competed, but it didn't have the same professional feel. Cmold, the main competitor, was bought by Moldflow several years back. I'm not sure if there are any new packages or not.

Well, I spent well over a decade designing the parts, molds (& sometimes making them) and then running the molding machines in my first business, so I generally know the lay of the land around molding.

The Mold Flow cost issue is easy. Make one mistake on a moderately complex 4 cavity mold, and the rework costs more than the initial price of Mold Flow @ around $13k.

Some of the things I'm doing require me to run a family set of parts for my assembly purposes, and that means making sure I can properly control fills for each cavity, hopefully with the help of Mold Flow, so that I make changes in the design phase, to get very near optimal before cutting steel.

The more advanced functions in Mold Flow of estimating costs using cycle times with specific resins and molding conditions, machine rates, etc. means more certainty in understanding and predicting costs on new projects.

Finally, some totally new parts using creative new approaches are simply a guess, as to whether you can make them work in the finished product, without driving cost throught the roof. That is where some analysis may pay the biggest dividends. If I screw up the initial concept and pay for a prototype mold, I can be out 2-3 months and $20-30k for the mold, and have an over expensive part or a heavy door stop. I have one of those in use as such right now.

The truth is few better products can get a higher price in the marketplace, so most new products have to not only be better but cost less to be able to take market share. So I'm looking for a better way to minimize time and cost to market and volume production costs.

Bo

matt wrote:

Bo wrote: ...

The alternative is to contract the work out. If you have a mold as a doorstop, contracting to an expert will save you more money than buying, learning and using software (and still making mistakes anyway).

To balance cavities in a family mold will require at least Mold Adviser.

Thanks Matt.

I've considered both ways, contracting and becoming knowledgable myself, & I think it best I expand my skills. I can waste too many hours going down a road in a design that I would not go if I had more accurate mold flow analysis when in early design stages.

Time, again, is something you can not recover once you lose it.

Bo

matt wrote:

One other option that's worked good for me is to set up cooperative engineering agreements with your mold builder(s) and bring them on very early in your design to help you engineer the part ahead of time. Most mold builders can run moldflows if needed to help you out, but a lot of times they can get you around problems without full blown analysis based on their experience.

That was our rationale for getting Part Adviser, and it seems to have worked out pretty much as we expected. We might run an analysis very early in a design to make sure we aren't barking up the wrong tree, then run a few analyses as we get ready to release to tooling to make sure everything looks OK and nail down gate locations.

As Matt said, you'll need to get Mold Adviser, which is quite a bit more, but it sounds like a good idea for you. We may want to head that direction as well, the next time we're flush with cash.

The Adviser packages are 2.5D, so they don't do a very good job on chunky parts. They indicate you are liable to have problems, but you need the 3D software to really understand what is going on. You also need the 3D software to analyze part warping. The bucks are so big here that I haven't had the courage to push it.

Amen!

Jerry Steiger Tripod Data Systems "take the garbage out, dear"