Wire Edm

Wire EDM has forever changed the way injection molds are made

Wire EDM has become such an integral part of plastic moldmaking that it is hard to imagine how things were done before. When it was first introduced in the 1980’s as a useful machine tool, the common use was in die-making. Over time though, this dramatically changed.

This new process was regarded as almost useless for moldmaking at first because molds have “blind” cavities, unlike stamping dies, which have “through” holes. Wire EDM, or WEDM, by necessity, requires a through hole to operate.

It didn’t take long, however, before WEDM began dominating many aspects of moldmaking.

How WEDM has become so useful in moldmaking

  • Electrodes for sinker EDM
  • Inserts
  • Insert pockets
  • Core pins
  • Mold bases
  • Ejector and core pin holes
  • Contoured parting lines
  • To reduce polishing

Not bad, for a machine once thought of as useless for moldmaking! From a moldmakers viewpoint, WEDM is priceless as a tool. The labor savings from grinding complex core pins, highly detailed inserts with compound angles, and contoured parting lines is truly significant. Not to mention the stress and headaches!


With a little creativity, many electrodes can be cut on the wire EDM. Generally, copper cuts much faster than graphite, and has the advantage of finer finishes and ability to EDM fine details. Premium grade graphite can be used, but is slower to cut.


Many inserts can be WEDM’d, then EDM’d in the sinker EDM. This marriage of technologies is one of the best examples of ingenuity using WEDM. Only minor grinding is required after EDMing to remove the tabs left from WEDM. Many of the tedious grinding operations of the past are now a distant memory, not many people miss them either!

Insert pockets

The pockets that are home to the inserts which were wired, now fit precisely. Nearly all of the pockets that are in difficult to reach locations are now routinely WEDM’d. The hassles of tapered sidewalls, fitting corners, as well as size and location are also now a thing of the past.

Core pins

Complex geometry that was previously milled or ground can be machined more accurately and quickly on a WEDM. Angles, sizes and complex radii are all commonly machined on using wire.

Mold bases

The pockets that hold cores and cavities, plus the holes and pockets that hold interlocks and other details can accurately be cut on a wire machine. An added benefit is that the slug from the pocket is no longer a pile of oily chips! It can be used for other components. An additional savings is in end mills and machine time, since most WEDM is unattended.

Ejector and core pin holes

Usually starter holes are drilled in the cores during CNC machining. Later, after heat-treat, the details are hand polished. Then the holes can be finished in the WEDM. This has many advantages: no bell-mouthing of holes, easier polishing, more accurate hole location and size, and better surface finish.

Contoured parting lines

Many shut-off surfaces and molding surfaces can be finish milled, but others lend themselves to wiring. This greatly increases the accuracy of the complex shapes.

Reduced polishing

Of all the operations to produce a high quality injection mold, polishing is the most vexing. There is often just no way around the fact that a highly skilled moldmaker must polish the mold, at great expense. This often causes a bottleneck in the scheduling and delivery. Using WEDM where applicable greatly helps to reduce the time spent polishing.

All in all, wire edm has had a dramatic and very positive impact on moldmaking. It is hard to imagine a modern shop without a WEDM, or access to a custom wire shop. Accuracy, speed, superior fit and finish are all the direct result of wire EDM.

Mold Mamufacturer China

Since China joined the world market in 1999 it has become a major supplier of high-quality plastic molds. The industry is centered in two main areas: GuangDong Province, which is about 20 km From KongKong, and Zhejiang Province, which is Closeto ShanHai.

There are lots of mold manufacturer china companies makes for an interesting cooperation between many companies. The ability to use specialized shops for various aspects of building plastic molds enables suppliers to attain quick deliveries while maintaining high quality.

Chinese moldmakers supply quality injection molds to companies all over the world. Molders find that communication and reliability set China apart from suppliers elsewhere.

China has a long tradition of craftsmanship

With the backdrop of the age-old skills of glass blowing and figurine making, China has embraced new technology to advance into the forefront of the global economy.

It quickly becomes evident for visitors that Chinese moldmakers have invested heavily in high-tech equipment. CNC EDM, WEDM, CMM’s for inspection of components and parts, robotics, lights out operations, SLA/SLS prototyping of samples, etc.

There are engineering companies that specialize in the project management of injection moldmaking and plastics molding. Because of the rather unique working relationship the various suppliers enjoy, this management has become refined to be very effective.

Service and Delivery

The mere fact that hundreds of global companies continue to buy plastic molds from China demonstrates the high level of service and delivery. On-time delivery of a trouble-free mold is crucial to make a profit. Buying a cheap mold that requires many hours of frustrating rework before it can run reliably gets old quickly.

An added benefit of doing business in China is the wonderful climate and delightful people! Plus, the labor laws and environmental regulations ensure that human rights are regarded and pollution standards are in place and observed.

Here are some recommended Chinese Moldmakers

GC precision Mould Co.ltd, is a highly developed mold manufacturer China company with many capabilities. They have a working relationship with various companies in the moldmaking areas of China and provide both plastic mold making and plastic molding service.

They produce high quality plastic molds for the automotive, medical, consumer, computer, and telecom industries. You will be able to communicate easily, receive timely progress reports, and can contact them at any time.

Their experience in engineering and their high level of moldmaking ability coupled with their communication set them apart. 

Looking for mold manufacturer china companies? Contact us to get a quote now

Mold Design

A proper mold design increases your chances of success in every way. Injection molding is difficult at best, a good 3D design will give you the edge.

Your moldmaker will be confident that the components will all fit, the dimensions all work together, and the mold will ultimately function as it should.

The molder will have confidence in the mold design, and the operation of the mold itself. You molder won’t be second guessing the design and it will help him process the parts.

Most of all, you customer will be delighted with a clean, flash-free, dimensionally correct plastic part.

What is important in good mold design?

  • A good design must be practical. The moldmaker must be able to produce the components in a logical, orderly manner to make money.Often, close tolerance dimensions are specified when a much looser tolerance could’ve easily done the job.Take an ejector pin plate, for example. Everyone knows that the thickness is basically irrelevant, but usually the dimension given is a close tolerance size. An experienced toolmaker will just ignore the tolerance and proceed, but nowadays, with the specialization of tasks in the shop, a less skilled operator would waste precious time holding an unreasonable tolerance.
  • The 3D geometry must be clean. The fast pace of moldmaking today makes it essential to have efficient, reliable software. The days of vague sketches, or toolmakers making up the design as they go are long gone. There are many excellent companies supplying very usable software programs for designing molds, as well as other things.CNC machines need clean geometry to run properly. If the design is sloppy and the translation of different software messy, the end result will show it. Plus, the operator will have a much easier time running the programs.
  • The design must be clear in it’s function. It is maddening for a toolmaker to spend hours deciphering what the designer means. Information that is assumed or omitted can delay the construction by days and cause unecessary errors.It is always much easier to include notes or details that show what is required than to search it out later on. Once the design is in process, and the information is available, why not simply give the moldmaker the same information? For example, a 3D drawing can visually clarify many questions.

Like almost everyone else in industry, designers have more to do than they can possibly handle. Here is a great resource for learning how to maximize your day, without stressing out in the process.
With the “Make Time For Success!” self-study program. 39 tips from the pros on managing time, effort, and others. Order the142-page ebook to reduce your stress and free up time.

Here are some established mold designers

Best Mold Design Small firm in the Chicago area with vast experience in mold design, as well as product design, 3D modeling, and invention development. They understand industry and the need for efficient and well planned designs that work. They serve the automotive, appliance, medical and consumer markets.

This is a good source to develop an idea, design a part, and design the mold or other tools required. Software includes Pro/Engineer, SolidWorks, and AutoCad.

Electrical Discharge Machining

The health and welfare of toolmakers that use graphite to make electrodes for use in the electrical discharge machining department should be a high priority for management. In addition to the health issues for the workers, the very expensive machinery, such as the EDM machines and milling machines, must be protected from the damaging effects of graphite dust.

Anyone who has worked with graphite in the manufacturing of electrical discharge machining electrodes is keenly aware of the need for proper dust removal during the machining process. Many ill-equipped shops have very little equipment to handle the dust generated during milling and grinding operations.


The MSDS (material safety data sheet) for the synthetic graphite used in EDM show that there are no carcinogenic properties associated with graphite. It is a chemically inert material and contains no volatile components. It is also used for medical purposes, such as implants and heart valves in the human body.

This is not to say that graphite is totally harmless though. It can be very irritating to the skin, eyes, and nasal passages. It can cause stinging, redness and watering of the eyes, and itching of the skin. This can be a very annoying experience when a toolmaker is expected to produce a close-tolerance electrode with a fine finish. The use of graphite in electrical discharge machining is increasing all the time, therefore the efficient removal of the dust is a priority that is often overlooked by management.

Controlling the Dust

The simple but very ineffective solution is to wear particle masks. Experience shows that this stop-gap measure is a failure. The mask soon is clogged with the fine dust and the poor guy making electrodes for electrical discharge machining is left breathing a disgusting blend of bad-breath and graphite dust!

Portable vacuums are the next best solution, but this also has many drawbacks. Often the filter in the portable shop vacuum is not fine enough to trap the microscopically sized particles, and they are simply blown back into the air. Also, because the vacuum hose is often cumbersome to manipulate, operators fail to properly align the hose to capture the most dust.

Many shops use a centralized vacuum system designed for the removal of fine dust particles, such as graphite. It is important to have enough air velocity in the vacuum system to be effective. It is recommended to have an air velocity of 500 ft. per minute and the air in the lines should travel at a rate of 2,000 ft. per minute in order to prevent the dust from settling inside the duct work.

With a centralized system it is much easier to efficiently manage the dust from the various machine tools because the system is more efficient and the hoses can be strategically placed. Special wheel guards are available for surface grinders that act as a turbo to remove the dust into the vacuum system.

Newer milling machines, which are more or less dedicated to electrode machining for electrical discharge machining, are equipped with extremely effective dust removal systems. The sealed chamber around the work area enables the vacuum to capture a high percentage of the dust. This development has dramatically reduced the amount of graphite dust in the shop environment.

An additional method of dust removal is the use of a curtain of coolant surrounding the milling cutter. This prevents the dust from ever escaping and is very efficient. This feature is available on some milling machines as well as an accessory that is easily installed.

A Clean Shop Environment

Graphite dust is highly conductive and has been responsible for the damage of many expensive tools and machines. Glass scales can give false measurements due to the settling of dust. Electronic equipment can be short-circuited by the dust as well. The grimy nature of graphite makes it especially annoying if it accumulates on work-benches and desks.

It is in the best interest of everyone to make every effort of maintain a clean and pleasant atmosphere in a moldmaking or electrical discharge machining shop. The toolmakers will be happier, the work will be better and the machinery will perform as it should. It is also very impressive for visitors to see a clean, dust-free shop.

Edm Machining

In EDM machining, the choice of electrode material can make a huge difference in the outcome of the job. Finding the right material can be a costly process of trial and error, or you can do a little research to save time and money.

Fortunately, there are basically only two main choices for most moldmaking applications. Of course, there are other materials in use, but they are mostly for special situations.Copper or graphite?

Moldmakers in Asia, Europe, and the USA have an ongoing debate as to which material is best for EDM machining, copper or graphite. Really, both choices are excellent, and your unique application and equipment will determine which is best for your needs.

EDM Graphite

Graphite is by far the most common electrode material used in the United States. EDM technology has advanced so that all new machines have circuitry that adapts to either graphite or copper.

Graphite has many outstanding characteristics, here is a partial list:

  • >Easy to machine
  • No need to redress grinding wheels; the details remain sharp almost indefinitely.
  • Ability to achieve fine finishes
  • Low wear
  • Very good for roughing operations, less expensive grades can be used

Grades of graphite

There are four primary grades of graphite used in sinker EDM.

  • Angstrofine- Less than 1 micron particle size. This is used when an extremely fine finish is required.
  • Ultrafine- Less than 5 micron particle size. Most finishing electrodes are of this type.
  • Superfine- 6-10 micron particle size. This type is generally used for roughing in cavities with larger details.
  • Fine- 11-20 micron particle size. Used for roughing in large cavities.

Cost of graphite

Choosing the correct grade of graphite for the job can mean substantial cost savings. For example: using an Ultafine grade for roughing a large cavity is wasting money. A lesser grade of graphite will actually outperform a fine grade in such a case.

Conversely, using a Fine grade instead of an Ultrafine grade to machine fine details will not only waste money, but not produce the desired results.

Good electrode material choices and correct EDM machining parameters can greatly affect the bottom line. It is important as well, to have an organized system of storing your graphite, so precious time is not wasted on using the wrong type by mistake. 


The use of edm copper in moldmaking is as old as EDM itself. Copper is much more common than graphite as an electrode material in Europe and Asia, though this is changing.

Copper has many advantages, as well as many disadvantages, when compared to graphite as a material for edm electrodes. A visit to nearly any EDM department will quickly reveal that copper is very much a useful material in sinker EDM.

Deciding which material fits your application is important, and time spent analyzing this can save you many headaches, not to mention time and money.

What are the advantages of edm copper?

  • Copper is more efficiently cut on WEDM machines. Copper cuts faster than graphite in WEDM. Highly detailed graphite electrodes, which were formerly manufactured on surface grinders, required many hours of highly skilled labor. The use of copper and WEDM to produce these electrodes has dramatically changed sinker EDM.
  • Copper is less likely to cause pits in the steel workpiece. The tendency of any electrode to “DC arc” is the curse of EDM. When the flushing is poor, machining conditions are ripe for a short circuit to occur in the EDM process, causing the tell-tale pits in the workpiece. Copper is much more forgiving and less likely to DC arc.
  • Copper is usually used to produce a finer finish in the steel. Copper electrodes are sometimes polished to reproduce the fine finish on the mold surface. Newer EDM machines have polishing settings that can produce mirror finishes, and usually copper is used.
  • Copper is the best for small cavities, especially where polishing is difficult. Because of it’s resistance to pitting and the finer finishes attainable, copper is often used in these applications. Adding tungsten to copper increases it’s excellent wear characteristics, but also is very difficult to machine.
  • Copper can be machined by coining. In this process, the copper is stamped with an image, just like a coin, and then used as an EDM electrode. This can be an excellent application for designs such as logos.
  • Copper is clean to machine and leaves no annoying dust. Also, tellurium copper leaves much less burr than pure copper.

What kind of edm copper should be used?

Tellurium copper (Telco) performs the same as pure copper as an electrode material. It has a huge advantage, however, because of it’s high machinability rating: 90% (free cutting brass = 100%). Pure copper has a rating of 20%.

Telco edm copper is highly recommended for use on machines which have been designed to work best with copper. It’s ease of conventional machining and fast WEDM speeds make it ideal for highly detailed, difficult to flush electrodes.

Why is copper more commonly used in Europe and Asia?

This happened for several reasons. When the first generation of machines were developed in these areas, the power supplies were R-C, or Resistor Condenser. Metallic electrodes such copper and brass were the only materials that efficiently performed in these machines.

Then, as newer generations of machines were developed, the use of edm copper was well established. Plus, EDM grade graphite was simply unavailable.

The use of copper has declined as technology has progressed. Newer EDM machines are designed to use graphite as well as copper. High speed machining centers are equipped with vacuum environments to remove the annoying graphite dust.


The world of EDM can be rather confusing; here is your source for everything in sinker EDM

Sinker EDM is such an essential part of building a plastic injection mold, that many of today’s products simply could not be produced without it.

Besides plastic injection molds, EDM is used for the precision machining of medical parts, aerospace parts, and other highly specialized products.

This is your source for supplies, such as graphite, copper, dielectric fluid, electrode holders, and machinery.

You can also find educational material that attempts to explain this rather mysterious process. Not so long ago, it was as much black art as science. Today, however, much of the mystery is removed due to CNC controls.

EDM is quite a stressful occupation, to put it mildly. It may not appear difficult, but the stress levels can be exhausting. Nearly every mold component that is EDM’d is in the final stages of manufacturing. The slightest mistake can become very costly, very quickly.

There are various methods of managing this stress, one of the most effective is a program developed by Mind Tools.

Back in the early days, electrodes were held by any number of methods: Vee-blocks, angle plates, vises, and many other home-made contraptions. It worked, and many amazing molds have been built using these methods.

Today, every progressive company uses at least one highly sophisticated system of EDM tooling. This tooling is essential for manufacturing, inspection, and the actual machining.

Electrode Materials

In moldmaking, there are a number of electrode materials to choose from. In actual practice, the selection usually is narrowed down to a few stand-by choices.

Graphite and copper are the dominate materials, with various other materials meeting the needs for special applications. 

Dielectric Fluids

EDM Dielectric fluid is a necessary part of the EDM process. As new types of fluids are developed, higher precision is possible, finer finishes are attainable, and the environmental impact is reduced. An added benefit is that your operators won’t smell like diesel fuel anymore either!

China Mold Manufacturer

A China mold manufacturer that produces high-quality plastic injection molds, as well as the plastic molded parts can help your company grow. Finding a reliable source can be a daunting task, and nobody can afford costly mistakes.

The companies listed here are known for their integrity, timeliness, fair pricing, and high quality. There are always cheaper sources to be found, but usually you get what you pay for. It is much better to focus on quality, especially since the rates are already so advantageous.

The offshore outsourcing debate is always open for discussion, but one thing is certain: it is a reality and not going to disappear anytime soon. Gaining a favorable position in the global economy makes sense and is a necessary part of business today.

Click below links for information on each plastic mold company

Sincere Tech is a plastic mold company Based in Gongguan city of China, with two facilities in mainland China, SINCERE TECH has built a reputation for high-quality injection molds and molded products. They run 24/7, have a high level of engineering expertise, and have high-end toolmaking and molding equipment. Sincere Tech is a trustworthy, reputable partner in global plastic injection molding.

Global Marketing requires a lot of homework

Taking steps to enter the global market is a major undertaking. There are many pitfalls, and also many opportunities to be taken advantage of. Time spent researching is well spent and can help to avoid costly and painful mistakes down the line. Some of the recommended reading here may be of interest. 

Plastic Injection Molding

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.

This page is for the “rest of the plastic mold company”

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

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 that 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.

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 moldmaking, 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.

Injection Mould

Like any profession, terminology for the injection mould, or injection mold (US) industries is unique. Interestingly, the terms don’t vary much from region to region.

This “glossary” should give you a reference for finding out what some of these things mean. When you’re in a meeting you can’t very well be asking what appears to be uninformed questions.

It is arranged in two categories: plastic injection molding and injection moldmaking. Many of the terms apply to both areas, after all you need a mold to do molding an what good is an injection mold without a plastic molder?

Plastic injection moldmaking terms

EDM terms

  • Burning: machining with an EDM machine, the actual operation of removing metal with the electrode. It’s burning because you can see zillions of sparks under the oil when it is machining.

  • Overburn: the distance that the sparks reach when they leave the electrode until they penetrate the steel workpiece. Usually this is from .002 to .015 inch. This is important because it controls much of the accuracy and finish of the detail produced. Can also be called spark gap or overcut.

  • zit: usually a small pit in the steel of a mold. Officially called a DC arc. Zits are bad because they are a flaw in the surface finish and will leave a “tit” on the plastic part.