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Plastic Mold Making

Plastic Mold Making

To achieve the desired mold productivity, many elements of plastic mold making and design must be intelligently incorporated. The basics of design for plastic mold making must be the starting point and then added to that, decisions made about a whole host of different design options must be made to work in concert with the basics to come up with an optimized mold design.Plastic Mold

Everyone is interested in having the lowest cost tool, but in plastic mold making, other considerations must also be included. Among these is the mould’s ability to be readily maintained, and kept in optimum condition throughout the mould’s useful life. A very low initial cost tool may prove to have a larger overall cost of operation; if for instance, lengthy maintenance procedures are required to keep the tool in operational condition throughout its life.

There are two general types of cavity and core inserts that should be considered when plastic mould making: Integrated and Nested or Split Structure. Each has its advantages and disadvantages, so the decision about which to choose when plastic mold making depends on the application and the required useful life of the mold.

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Integrated Cavity

The integrated cavity is cut directly into the mold base plates. It requires the fewest number of parts and is the simplest to produce, so often (though not always) this is the least expensive to produce in terms of initial investment. However, as stated, this is not always the least expensive alternative when considering the cost of the tool over the life of the part.

Some of the Advantages of Integrated Cavity Mold Making include:

• More practical for large or odd-shaped parts, such as automotive body panels and similarly shaped parts.

• Least amount of machining – so lower initial cost.

• Least amount of mold materials used – so lower materials cost.

Conversely, some of the Disadvantages of Integrated Cavity Mold Making include:

• Requires larger, more expensive machines to make the molds, and no components may be made in parallel, so they often have a longer lead time to produce.

• Most costly, difficult and longer lead time to modify in the event revisions are required.

• Costly and difficult to repair with longer down times when the mold wears or is damaged during its useful life.

Nested Cavity

When making a nested cavity plastic mold, cutouts are made in the mold base to receive nested parts that form the mold cavities that produce the finished parts. While this has more components than the Integrated Cavity type, often the advantages of plastic mold making using this method far outweigh the disadvantages.Plastic molds

Advantages to using Nested Cavity plastic molds making:

Complex geometries may be more easily formed when using nested cavities, for example, multi-pin electrical connectors are nearly always made with nested cavity tools.

Improved materials may be more easily incorporated into nested cavity molds for reduced wear and improved mold temperature control ability.

Damaged or worn components can be quickly and inexpensively replaced to minimize downtime.

Some of the disadvantages of using Nested Cavity plastic mold making include:

• Higher initial material costs

• More machining required in some cases, as both the mold base and the cavities require precision manufacture. (However, most of the machining may be performed on smaller, faster and less expensive machines.)

Consult with your mold maker to decide which of these two different plastic mold making philosophies are most suitable for your specific application. if you want to know more about us please got to our home page to know more about us

Precision Injection Mold Making

Precision Measurement And Injection Mold Making

It is remarkable that it is possible to open a package from Sweden, clean up EDM tool, and install it in an engine lathe spindle made in upstate New York, and indicate the run-out with a dial indicator made in Switzerland, held by a magnetic base made in Japan. This is amazing in itself, but the truly amazing thing is that it all works, quite well!

In this example, which actually happened to me, the run-out was less than .0001in/.0025 mm, right out of the box, first try. This is what precision tool measurement is all about.

The number of precision tools used by an injection mold maker are numerous. A partial list would include:

Precision measurement tools

  • Granite surface plate
  • Surface gage
  • Dial indicator
  • Height master/Cadillac gage
  • Gage blocks
  • Pin gages
  • Sine plate
  • Magnetic squaring block
  • Vee-block
  • Precision micrometers
  • Spin fixture

One of the more challenging aspects of building a mold is to have all of the various measuring tools calibrated to the same standard. This is why the EDM chuck from Sweden fit in the American lathe spindle: the accuracy was traceable to a common standard.

It doesn’t mean much if you are accurate within .0002 in., if your micrometer is off! It just won’t work. Shops need to have a master set of gage blocks that are traceable to the NIST, or National Institute of Standards and Technology. This is not as hard as it sounds, you just need to invest in a good set of gage blocks, not some made by child labor in a developing nation.

The proper care and use of these expensive tools is critical as well. They need to be treated with respect, handled carefully, kept free from rust and grinding grit. They need to have a clean storage place, with a grit-free surface on which to sit.

There are many places that you can cut costs in Plastic mold making, precision measurement tools is not one of them. It simply makes no sense to save money by buying a cheap dial indicator, for example. It is only going to haunt you in the long run. The same holds true for gage blocks, micrometers, squaring blocks, sine plates and so on.

With large items, such as the optical comparator or coordinate measuring machine, it is especially important to obtain a reliable tool. Valuable shop time can be quickly consumed with trouble-shooting a low quality machine. Not only that, but what if the measurements are unreliable? The mistakes can become extremely expensive and will quickly erase the initial savings.

Reliable precision measurement manufacturers

 Starrett Brown-and Sharpe Interapid Girod
 Etalon Mitutoyo Suburban Mahr
 Tesa Hermann Schmidt OGP Magnets
 Harig Micro-Vu Mitutoyo Zeiss

How To Make A Mold For Plastic Injection

How To Make A Plastic Mold For Plastic Injection

If you want to learn how to make a plastic mold for plastic injection, be prepared for a concentrated effort! The skill required to build plastic injection molds is considerable and you must be prepared to diligently apply yourself, for quite a lengthy period of time.

However, if you are truly motivated and have basic machining skills, it is entirely possible to learn how to make a mold for plastic injection own.

You will, of course, need to learn about CNC milling, EDM machining, mold polishing, WEDM, CAD mold design and mold assembly. Many community colleges have evening programs where you can work, plus they have textbooks to teach you.

Learn how to make a mold for plastic injection

Generally, in the United States anyway, you must take classes, either at a technical college, or a night school. This is done in combination with working as an apprentice, usually for 4 additional years.

Personally, I completed a 2-year full-time course at a very good technical college in Minnesota. During this time I worked as a machinist in local shops. This is a great way to learn how to make a mold for plastic injection.

Upon graduation, I was hired as an apprentice Plastic mold maker. Because I had finished my classes, I was not required to take any evening courses. After registering with the state, we had periodic inspections of the type of apprentice work I was doing.

plastic mold | plastic injection mould

plastic mold | plastic injection mould

Probably this was to ensure that nobody was taking advantage of me and that I was receiving the agreed upon training. It also ensured that my pay was increasing over time, until I reached the “journeyman” level.

Skills needed to learn how to make a mold for plastic

 Listening

 Thinking

 Watching

 Imagining

 Milling

  Lathe work

  Grinding

 Drilling

 Geometry

 Trigonometry

 CAD

  Design

  Polishing

 Assembly

 Wiring

  Overtime

 EDM

WEDM

 CNC Milling

 Inspection

Time and space would not allow for anyone to attempt to explain how to make plastic molds for plastic injection on a website. It could be done as an ebook, though I have never seen one. There are several good books that explain the process in great detail, and, of course, there are textbooks available.

The best way to learn how to make a mold for plastic injection is to become an apprentice. If you already are an apprentice, you can learn a great deal from plastics journals, such as Mold making Technology and EDM Today.

Plastic Injection Molding Secret

Finally, the rest of the company can secretly learn about plastic injection molding

Sometimes you just have to nod your head and pretend that you know what it is they are talking about. On the other hand, it sure would be nice to really understand how plastic injection molding works and what all those terms mean.

Often, terms like overmolding, two-shot molding, galling, hobbed-in, coined, toasted, NFG, shut-off, etc, etc, are just taken for granted. And usually, people don’t like to reveal that they just don’t know.
Really, it is in everyone’s best interest to truly have a fundamental grasp of the how and why of plastic injection molding. The explanations offered here are not technical, but rather a general idea of the concepts.

Some of the processes involved in plastics molding and mold making are easy to grasp, others are downright mysterious to an outsider. Click on any process below to learn more.


 What about EDM, or electrical discharge machining?

Of all the methods used to produce a plastic injection mold, EDM is the least understood. How can a non-technical person grasp it when you usually can’t even see what is going on? Since the workpiece is usually submerged in a tank of smelly, oily fluid, who could know what it’s all about?

The main reason to have a basic understanding of EDM is because it is the most essential process involved in plastic injection moldmaking. Before EDM, many operations were extremely difficult and time consuming.

Other names for EDM are: ram EDM, ED, spark erosion, and burner.

What about WEDM or wire electrical discharge machining? WEDM is sort of a cousin to EDM, in that it was developed quite a bit later. Wire EDM was originally thought to have a very limited application in plastic injection mold making, but it has proven to be indispensable.

Mold designers have become very creative in applying WEDM to build injection molds. In the not-so-distant-past, much of what is “wired ” was done on surface grinders. This was very tedious and difficult, requiring a high level of skill and expertise.

Much of what is done with WEDM was simply impossible otherwise. The shapes and contours attainable are sometimes only possible with this technology. go to one of the best mold manufacturer China home page to know more.

Rapid Injection Molding

Rapid Injection Molding

Rapid injection molding is exactly what the name implies, but multiplied by a factor of 10! It is hard to imagine that anyone could offer a service that can guarantee a fully functioning injection mold in a day or two, but that is actually the case.

This is precisely what rapid injection molding is all about. Rapid, as in very rapid! These molds are made of high-grade aluminum and can produce anywhere from a few parts to thousands.

Personally, I have worked on many aluminum molds that produce high-quality parts even after several hundreds of thousands of cycles. At first, I was highly sceptical, but after several years of making injection molding prototypes, It became routine.

plastic molding

rapid injection molding

How does rapid injection molding work?

It works by automating as much as possible in the plastic mold making procedure. By taking the customer’s 3-D model and automating the design and manufacture of the mold, the lead times are cut down to a fraction of the conventional process.

One of the central parts of the automation process lies in the design of the plastic part. By working with knowledgeable designers, many features, such as undercuts, can be minimized or eliminated.

Some of the features that must be considered are:

  • Part draft angles and radii
  • Ejection
  • Using straight pulls whenever possible
  • Simple approaches to side actions
  • The CNC milling process
  • Part size limits

What are the advantages of rapid injection molding?

  • A way to bridge the time gap between prototype and full production. If you need a working injection mold right now, this is the answer.
  • Short run production to get your product in the marketplace immediately.
  • Gives engineers a working model to approach a full-blown design for a production tool.

What are the disadvantages of rapid injection molding?

  • The aluminium molds are low production.
  • Works best for simpler parts with minimal side action and undercuts.
  • EDM machining is eliminated, thus some detail may be sacrificed.
  • The entire core and cavity are high-speed CNC machined, often on 5-axis CNC machines, therefore the design has limitations.

Is rapid injection molding expensive?

Surprisingly, the cost is quite reasonable, though there is always a premium to pay for extremely quick turnaround. Typically though, the cost is much less than might be expected. This is due to the highly developed automation process of this type of plastic injection mould making.

Conclusion

Rapid injection molding is a niche market segment of injection mold making. It serves a highly specialized marketplace, yet is very important within the niche. The ability to get your injection molded plastic part to market in a matter of days is very valuable to the right company.

Also, the ability to bridge the gap between prototype and high production is a very useful tool for custom injection molders.

A leading plastic mold company who is professional in rapid injection molding is plasticmold.net, in China. They have just about everything you might need when it concerns rapid injection molding.