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Working all along with polymer manufacturers, certain tricks I have learnt.
As all of you are aware that there are two types of recycled or reground materials, such as, ex-factory and post-consumer. It is easy to mix ex-factory reground, as the history is known. Whereas, it is a challenge to use post consumer recycled material.

In Auto, Home Appliances etc. injection molded critical products, where product validation is required, use of post consumer recycled material is not advisable. Only factory regrind can be used. There are some low end applications, where suitable post consumer recycled material can be used with an acceptable level.
As someone who first became involved with Water Assisted Injection Molding in 1998 (and who initially actively tried to promote it) we soon realized that the principle benefit of the technology (fast cooling of the plastic in contact with the water bubble) is also its limiting factor for certain part geometries.

Parts with no attached wall sections (i.e. pipes and media ducts) can successfully be produced with water assisted injection molding at cycle times that are up to 40% shorter than gas assisted injection molding. However, even with these types of parts, if the pipe wall section is sufficiently large you will tend to get "voiding" in the wall section. This is due to the water producing an instantaneous frozen skin when it comes into contact with the molten polymer. Thus, even if the water is at 300 BarG pressure, that pressure cannot be transmitted through the polymer melt as it is already contained within a "frozen" tube. If this tube (water channel) is attached to a wall section (chair molding) it also means that the surrounding plastic cannot be pressurized by the water channel, this can lead to dimensional issues and also sinkage if there are any nearby bosses or ribs.
I took a quick look at the number of machines currently and in consideration of adding more capacity and significantly increasing the size of the operation, I strongly recommend you get a well experienced plastics engineer with injection molding process, tooling and machine expertise on board. Training is great, but a consistent approach is critical. Set-up techs tend to revert back to their old ways, especially when they've never had formal training and have been "brought up" in the business and feel they are constantly fighting fires. So many of these folks were taught wrong in the first place, it takes a well-liked, hands on type of leader to help them learn and implement the right way to approach mold trials, and subsequent start-ups. You have a huge job ahead of you, but if you plan to expand your operation it would be most beneficial to have the right type of expertise in house both for training and to take advantage of their knowledge as it pertains to making the most of your expansion in the facility layout and equipment selection, work flow planning, etc.
The benefits of hot runner Manifolds is significant when calculating material consumption and injection molding cycle time, however, many injection molds that are designed and built with hot runner Manifolds DO NOT consider all of the variables that the Part/Product may be changed during the R&D process. I've always favored building a conventional injection mold with cold drops as a vehicle to prove out a Part/Design before committing to a hot runner mold. This allows the typical tweaking of Gate Locations and Sizes to be modified in accordance with best molding parameters and overall part stability/performance/cosmetics prior to going to a hot runner mold----which will not have the options to revise gate location(s), etc. A change of material/resin during R&D may also have a dramatic effect on a hot runner manifold design, which, in most cases can be accommodated in a cold drop injection mold.
For those people that commonly deal with complex injection molds that have Lifters, Slides and require Ejector systems that seem to leave very little area for cooling lines. What are my options? Sure, I'd love to drill my 7/16" (11mm) diameter lines across the core block and place them fairly close to the part, let's say .150" (approx. 4mm) distance and in uniform rows so that the cooling will be uniform. But I can't navigate through the maze of components that restrict a straight path for a cooling line. So my cooling options now go to plan "B", perhaps dropping in a vertical "Bubbler" to cascade a single point of cooling in whatever area I can fit it in. Or maybe fit in a be copper insert to enhance thermal flow and try to get some water to it further away from the part geometry. Now I'm looking at the cavity side----Great! no ejectors, but the part geometry is curved, so I can't follow the cavity surface with a straight drilled cooling line, well, as long as I can get a few lines active, even though the cooling might not be balanced to the cavity of the part because the cooling line is more effective at the tangent/closest point to the part cavity. Oh! Now it becomes obvious that I have much greater cooling on the cavity side than the Core Side-----No problem, I can adjust the flow rate for each side until a good injection molding process is obtained, after all, I have designed the cooling lines for Turbulent Flow, so if I have enough water pressure/flow rate, I can make it happen. And now I am asked to calculate this cooling design!!!!
(A) 'Why is the cooling time THAT long" -
ANSWER: At that exit temperature, after everything else has been optimized, it's the shortest time to get customer acceptable parts
WRONG answer - The mold maker screwed up the shrinkage

(B) "in plain language how do you duplicate the process in machine "A" when you put that mold in machine "B" that has a different size/capacity injection unit and clamp and not start from scratch?"
ANSWER - it's all volumetric translations. The part must fill in the same time. It's volume, required melt or mold temperature, open/close distances, packing pressures or any of the time settings hasn't changed. Water temp has to be the same, water flow must be turbulent although the Reynolds Number might be different.

C) Even better "How do you know that waterline hookup is (1) optimal for that mold and (2) identical to the last five times you ran it?"

YOUR ANSWER: reynolds calculation and/or delta P as for pattern I consult the water line diagram. CORRECT
COMMENT - you'd be amazed how many people don't use waterline diagrams.
I've met too many people who go through injection molding training courses (VERY expensive ones - limiting the attendees to larger companies) who have a diploma on the wall who can't explain the answers to simple questions such as (A) 'Why is the cooling time THAT long" - unacceptable answer: 'it makes goods parts' ,(B) "in plain language how do you duplicate the process in machine "A" when you put that mold in machine "B" that has a different size/capacity injection unit and clamp and not start from scratch?" (C) even better "How do you know that waterline hookup is (1) optimal for that injection mold and (2) identical to the last five times you ran it?" (D) And, the ultimate ship sinker "what is the ONE cause of short shots (or any other of the 18 routine molded part defects) that explains every solution you're going to try to correct this defect?"

These questions should be easy. But most graduates from the injection molding training courses I've seen, who've been declared "Trained and Certified" can't answer those questions.
There is an inter-mingling of best QUALITY and best VALUE. One way the quality of the injection mold is explicitly defined is the SPI mold construction class. A higher QUALITY injection mold is a higher quality injection mold, but it may be a lower VALUE if it is overkill for all the other requirements and way more expensive than lower piece cost could offset. An adequate quality injection mold is usually the best value; unless, it is likely the volume of the product is volatile and may increase substantially with short lead time. Naturally, "an adequate mold" or the "Best Value" is somewhat subjective and should be agreed upon between customer and supplier for a happy relationship.

Don't confuse quality with value. Value is an economic balance between purchase price, piece price at the volumes to be run, and adequate precision for the application. The goal is adequate quality tooling for best value, not the highest quality tooling that you cannot afford. A Ferrari F1 is higher quality construction than a Chevrolet Cobalt, but for most people the Cobalt is a better fit to the need to go get the groceries or the kids, and therefore a better value.
I have been in the mold making industry since 1963, became a master mold maker, was a sole proprietor designing plastic injection and thermoset molds for 13 years in United States, was hired by my current company in 1990 and learned to work with CAD (NX) to be exact, I'm 67 and still love to design molds, I find it interesting when apprentices ask which text books they need to read in order to learn how to design a plastic injection mold, to which I always answer that they a writing their own book as they learn from the their colleagues on the shop floor, there are some text books as well but on the job training is a must.

I believe the future is bright here in the United States, we will level the playing field eventually, after all, mold making made the United States the nation is today, without mold makers of all kinds we would not enjoy life as we know it today here, and throughout the world.
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