The best way for you to learn mold design would be to work for a company that designs and makes a lot of molds. Do some research and try to get a job with a mold company that has a very good reputation. Try to find someone to learn from that has a lot of experience, good working skills and knowledge of mold design, and then learn everything from him or her that you can.

While having an education is good it will not give you everything you need to be a successful mold designer. You can learn to use CAD software and get a general idea of how molds are made in school but there is nothing like real life hands on experiences in the factory to learn from.

We spoke with a local injection molder who is very experienced and produces high end plastic parts for the medical industry. When they examined the parts, they noted the flow path, how it creates and positions the weld line, and was almost sure that the flow was trapping air in the part, at the weld line. There was a very slight discoloration along the weld line, but no voids or bubbles in the part. The air is compressed at the weld line and weakens the line. Several mold design features can be incorporated to resolve or prevent this (some of which we have incorporated into the mold modifications):

• move the gate to change the flow direction and path (done in the modification of our injection mold)
• add an ejector pin at the site of the trapped air, to vent the air (added pin at the remaining weld line after gate was moved, ensuring venting).
• vent the whole perimeter of the part mold.
• locate the gate at the thickest section of the part.

To get a quality injection molded part, besides a quality mold, you need to know how to setup the process working condition correctly, optimum working condition setting provides the minimum cycle time, lower scraps rate, stable performance and quality parts, a complete injection molding process includes: filling stage, compression stage(packing), holding pressure stage, cooling stage, ejection. There are three major elements to consider to setup a correct working condition: temperature, pressure time.

Let's face it, those of us in the plastics molding industry typically have to deal with sink marks with most parts. We all understand that the Geometry, Variations in Wall stock and Interior features sometimes go beyond design guidelines and result in sink marks. For reducing sink marks there are some process adjustments that may resolve the problem. If you have Quality Tooling and an accurate water temperature controller, you might be able to "Freeze Off" the Cavity side of the part while keeping a good hold pressure on the resin. This technique would usually add time to the total cycle but perhaps worth it. I have also used the RHRC (Rapid Heat Rapid Cool) process which is not used at many molders since it requires a Steam System that is piped to the Molding Presses

There are some reasons to cause the lack of material in final injection molded parts. First of all it starts with the mold design. Second we have the plastics. Third we have the injection molding machine. Forth we have the people involved orchestrating the whole concert. Fifth we have the machine and sixth we have the environment. Last but not least we have the process itself.

Starting with the injection mold. The mold has to have a design that allows you to produce good plastic parts. Clear for all of us every injection mold has a process window. That means that whatever your molding machine is doing at a certain viscosity the mold needs a certain pressure within a certain time limit in the cavity. This is unique for each and every injection mold like a finger print.

Mold assembly is one of the most critical steps of mold making procedure, all the parts machined or purchased need to be put together and required to be work functionality. Mold assembly job requires comprehensive understanding of mold structure as well as injection molding. Quality of mold assembly determines the mold precision, injection productivity. The work instructions below can be treated as a guide for mold makers.

All parts are machined correct and clean, the work tools required are available and the workplace is well organized, before assembling the mold, all the components must be check and verified.

There are more for different types of mold structure, such as 3 plate mold, they have unique design of latch lock, limited pull plate, runner plate etc. and for hot runner molds, they have special design for hot runner manifold plate, and installation of hot nozzle wiring, plugging etc.

Soft start is designed to make sure any moisture that may get into the heaters will be baked out at low slow temperature rise before higher temperatures are applied. This will prevent your heaters burning out prematurely. Many times when I have to trouble shoot a hot runner in the field, a customer has issues starting up a system that has been running a filled resin. The suggestion of cleaning out the filed resin at shut down would not void a warranty. In fact, if the hot runner supplier heard that they would support it.

The injection molding machine outputs cannot be set, but the inputs can be each time you set the injection mold. Some of these set points, like mold temperature and barrel temperatures can be set. Of course this depends on which factors are the most critical to the injection molding process. If you had ability to perform a simple screening DOE before you put a specific injection mold into production, Minitab can pare to out the most significant inputs. If nothing else, these would be the ones to monitor. However, you'd likely want to capture fill time, cushion, screw recovery (loading time) and cycle time (especially if the machine is not run automatically.

Bottom line, if you have unlimited funds to purchase advanced monitoring systems and have employees that know how to operate them properly and analyze the data they produce, then by all means use them. But if you are dependent on your machine operators to produce good product, you must give them simple tools that they can understand and use while they are right at the injection molding machine. And they can monitor virtually every shot in real time, so if something does drift, or a machine or mold issue does arise, they can notify appropriate engineering personnel immediately.

Using the mold to make plastic parts or Nylon part, depending on the application, one long core pin from one end of part. Cores mounted on top of mold.

The plastics are molded in the vertical position in the mold. The ID of these parts or Zero draft, to allow for the mixing elements to be inserted without regard to position - they fit either way and must be a snug fit to the ID of the nozzle. Water bubblers run the entire length of each core with a threaded tip on the end- water tight with a little super glue.

Proper location of the gate point will be directly affect the quality of the injection molded parts gate location selection should follow the following principles:

1. Gate location should be chosen in parting surface, so that it would be easier for machining and maintenance.
2. The runner should be designed even, mold flow distance and sectional size in balance can achieved stable molding quality.
3. Gating location should be on the thick-wall area so it ensure the cavity can be filled completed.
4. The mold flow should not be right on the inserts or lifter, high pushing pressure of melt flow would probably deform the inserts.
5. Try to avoid weld marks or weld lines created in the critical surface, changing location of gating and try to make the weld line on uncritical surface.
6. Consider the venting when design the gating, make sure the end of the mold flow have good venting.
7. Gates should be easily removed and gate mark should not affect the appearance of the molded parts.

By applying all the above it is arrived per cavity about 3.4 KN force will be required to pull out the core, then for 4 cavities and multiplying by 1.5 as w.o spring load concept consideration, total force needed to pull out the 4 core pins for this 4 cavity mold will be around 21 KN or 2140 Kgf.

Draft will be, for the ID:15mm, the core pin dia will be at the end it is Dia 15mm and in the bottom 14.1, even the core pins are provided as two halfs (155mm Length each) to match the overall length 310 from top and bottom. Both side the core pulling will be done.

There are thousands reason to use hot runner system in injection molding but seems lacking of info not prefer the hot runner. As I know the hot runner can be considered as the extension of the barrel. In some cases it combines with the injection gate that it can inject to the part directly.