There's a big difference between making a good mold and saving money on manufacturing. You can make a good mold anywhere in the world. However having a good mold made is only a small part of the equation. It takes 6-12 weeks to make a tool. Material, product and production quality is a much bigger part and it can span years.
It's easy to save money on mold and lose tenfold on parts. What we do is make the mold in the most cost effective place worldwide but we always run production here in China. We tried to run production overseas only to come back with our tail between our legs after having to criss-cross the globe flying engineers to scratch their heads over supplier based failures spending weeks in hotels and eroding any potential savings.
That injection molding machines are not in the simulation is a problem we have to keep in mind. So there is the pressure loss in the nozzle. Some people create the nozzle in CAD to get this in the simulation. But what is with the quality of the injection molding machine. Old or new. Is the return valve working? Compression of the melt in the cylinder is not considered of simulation.
To increase the life expectancy of an injection mold, you need to do careful maintenance and avoid operation mistakes during molding plastic products. Water lines can be a major problem. Run treated water or build from stainless. Build the tool solid, large pins, support pins, locks etc. use the mold safety settings on the press. Chart the number of shots it takes for the mold to start to run less well, and set up a plan to pull, service and check it before it hits that number. Replace worn parts. Greasing the moving parts before they start to make noise. Blowing down the water lines when the plastic injection mold is pulled from the press, or using quick disconnects that seal the water lines when they are disconnected.
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.
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?
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.
Many oversea buyers intend to send their inquiries to a bunch of Chinese plastic injection mold makers before they placed order to one of them, choices sometimes just simply made base on price. If you are lucky enough, you could probably get a qualified molded product at the cheapest price. But what about the next time? Your business success should not be hanging on odds.
Whenever you get a quotation from a China mould supplier, you better have your own sense to estimate if it's competitive or reasonable or it's over-charged. It's very much necessary to understand the actual mold price in China.
Cost of a plastic molded part includes raw material, injection molding, labor cost, packing, transportation, management, and profit. Let ‘s get into each items one by one.
Plastic parts produced by the injection molding process are usually long lived consumer products. It's suitability depends on the properties of the finished part and surface quality, it required a lot of experiences of raw materials, processing condition, injection molding parameter to get optimum results. The reasons to cause problems could not be a certain answer as the processing condition is always different, on the basis of an individual case a decision has to be made as to whether simple and rapid fault correction is possible or whether intervention is the design of the parts or the layout of the mold and gating is necessary.
If the resin is in powder form then used high power magnets to remove them, and if it is in the form of granules then melt it in big volume in any bucket type (in this way metal parts will moved down in bottom) then in its molten state put it in extruder for re-granules or processing (molding).
Your Part size and Weight will also determine Press Size which will narrow the selection of manufactures, you will see that among your list of plastic injection molding machines, there are some that are very well suited for smaller parts whereas other excel in very large tonnage presses. The Resin used in your applications will also determine your choice of Barrel specified on your selection of the injection molding machines, this will relate to your part weight as it must be calculated to resident time in the barrel.
In general most feed throat temps are from 95 deg (f) to no more than 130 deg (f). There are some injection machines that have specific feed throat temperature specs. Husky PET machines are an example. However most injection machines do not. There are several things to avoid. Do not get any part of the feed throat cool enough to cause condensation. Do not let the feed throat get hot enough to let the material soften and clump. Outside these cautions you will usually find little effect of the process from FT temperature.
You are not alone with your difficulty finding talented injection molding technicians. With the industry down turn cycles and mass closing of many injection molding companies
most of the junior technicians got laid off and found work in other industries. Now that our industry has taken a positive upturn there is no one in the talent pool to fill these roles. I blame the bean counters for this problem. They sacrificed the technical floor personal to secure their profit margin, knowing that at some time in the future the industry would pick up. Now they are scratching their heads wondering what they are going to do.