Spend the money on mold filling simulation analysis and allow the mold flow analyst to do the same things that create the variation, analyzing potential variables and review the results with your part designers, this will allow one the “wiggle” room needed for the best outcome. For example:
After running basic mold filling simulations - based on best practices or using molding parameters based on previous similar designs – start making simulation changes that allow one to understand the limits of the design tolerances based on varying the process – change materials, change the pressure, change the mold/process temperatures, change the filling parameters and gate freeze options to understand desired effects and those molding parameters that result in unwanted solutions. Each part geometry has its own optimized solution.
After we finish assembling a new mold, we need to launch it and do a mold tryout.
The mold designer and mold maker sometimes made mistakes, any small mistakes could lead to major damage of the injection mold, the purpose of mold tryout is to find out any potential defects and ensure the mold perform stable and efficiency during molding production. If the tryout process did not follow reasonable procedures and make the appropriate records, then we cannot guarantee smooth production, this could cause serious problem, it means much higher cost or even delay for mass production.
Just as well I would recommend you that any software you must verify first an structural analysis prior to validate your injection simulation to ensure you will not find bubbles, air trap and weld lines in areas of high or low strength. And also is very important to document the evidence you found, and take care later in a meeting with the tolling that will develop the tooling and take this into account in the development of possible new flow leaders, vents or put some specific flow to improve special parts of your model, don't forget to invite, or call to your resin representative, because they have some tunning recommendations regarding final gate designs as well processing guide lines.
As a injection mold manufacturer, we received a lot of inquiries from our website and B2B, an interesting phenomenon is the professional/ potential customers usually very clear about what they need, the information provided by them are very specific, we take serious for this kind of inquiries. On the other hand, inquiries with very little information could be a signal of no intention to purchase; we do not put it in priority. This explains why you get very few replies when you send inquiries to many injection mold manufacturers, you did not inquiry like a professional.
All the mold and injection molding project are custom manufacturing project, so it's not like other common product, the demands are always diverse, injection mold factories need to know the detailed demands of the customer before they can provide the most suitable solution, it's much more than pricing, it's a custom made solution.
Without doubt having own fully equipped tool room in plastic injection molding company has huge benefits over the years in terms of winning new customers and not just for injection mold tooling. We often describe the tool room as the "heart" of the business as although it's only a small part of our companies turnover it's what is produced in there that goes onto to contribute to that turnover. We need to make injection molds that run at a predicted cycle times and that don't cause a problem in the mold shop so we cannot compromise on the quality.
It is always best combination to have tool room and plastic part producing facility under one management. We are a company in China having only injection mold making facility at one location and component manufacturing facility at other location, though just five minutes away from each other. Here the advantage is that some customers come to us only to buy molds while some customers are interested in buying molds and plastic parts. Also tool room engineers have a different way of thinking while a production engineer thinks differently. So it is better that these two facilities are kept separate.
Mold design is the start of any successful mold-making project, so a careful evaluation and optimization process is very much necessary, review the design to verify the plastic parts requirements and mold manufacturability are all satisfied.
- Is there a "parts to customer" promised date?
- Has the mold completion date been established?
- Has the cavity level been established?
- Has the mold cost quote been completed?
- Has the cycle time been established?
- Has the material to be molded been determined?
- Is existing product available?
- If 7 is yes, should the existing gate location be used?
- If 7 is yes, is the product symmetrical in design?
- Are maintenance costs built into the price?
We are investigating an alternative method of making 200 small flat curved parts that are symmetrical relative to the midplane. Both sides are identical so the two mold cavities are identical. We are looking for an easy to cast material that has strength/toughness properties as HDPE or even as UHMW PE. The parts should never break but are allowed to bend (somewhat or even a lot) under exceptionally heavy loads. It can be a net casting or machined after casting but tolerances are not important as the parts are not attached to anything.
One of your choices can be Casting Polyurethane. Based on the situation, you must use Polyether - TDI base casting material if the environment is wet or these parts will work in water. This type of Polyurethane has moderate to high tensile properties and excellent resistant against water. But if you need a high property such as tensile strength or abrasion resistant, it's better to use Polyester- MDI or Polyester - TDI. You can use every colorant for this purpose.
I work for a company that sells Moldflow and provides Moldflow services nationwide, but we have been seeing that Moldflow is making a move towards the front end of the design cycle and more design engineers are getting involved using simulation up front. It can help them in a number of ways, and it is much more cost effective to do your simulations early on. With tool makers doing less of it, and simply moving to creating molds per the specs of the designers, many make additional money off reworks - which everyone is looking to do in this economy. Thus, companies are taking back control of their designs...it is an interesting shift from the way Moldflow was used in the past vs. how its usage is evolving.
China has a wide variety of skill sets available from high end to the lowest low. The culture is open to interpretation when the injection mold shop decides how to design the cavitation structures. I suggest having your own injection mold tooling expert and engineering determine the way the cavities function. I also suggest having certifications on hand for all the steel used in the plastic injection molds. This would include all receipts and traceability documentation. There are different levels of quality in China for steel and you made have a variety of heat transfer issues associated with it.
In short, the USA and others are leveraging the moment and getting some quality plastic injection molds out of China. Check the references and make sure you call non-competing companies to mitigate your risks. Also hire people that project managed these types of injection mold suppliers to deliver exactly what you ordered.
Multi-cavity molds produced parts in a much higher efficiency way, it's employed frequently on the occasion when the demands volume is high, the number of the cavities and mold construction depend on both economic and technical factors, quantity of parts to be molded at one cycle, required cycle time, and unit price are related with mold making cost. See below figure, mold cost and plastic parts cost need to be considered to achieved the best result of the project.
There are a few points need to be pay attention when we decide the numbers of cavity.
Some suggestions for effectively using in-house scrap, whether for injection molding, extrusion, vacuum forming (which generates a lot of offcuts).
1. For companies producing multiple products, a good strategy would be to use up in-house scrap in components/molding with lesser service severity requirements molded from the same polymer. e.g. scrap from moldings of high aesthetic requirements could be used up in molding where aesthetics are not so important/darker in color. Load bearing molding regrind could be used up in non-load bearing items.
Sometimes it is safer to use up all the regrind in a dark, non-critical item if such an item is in the manufacturing mix in sufficient numbers to be a scrap sink.
A typical injection mold RFQ that we see includes CAD files, quantities to quote, EAU quantities, on occasion program life expectancy and resin specifications. The RFQ information is quite limited considering the capital expenditure that will be based on the quotations received, not just the initial capital requirement, but production ramifications as well. The determinations as to press size, mold quality, sample size, length of sample size, run time, mold qualification requirements even basics such as tolerance requirements are left to the quoting facility to determine in the initial RFQ/quote package.