The Plastic Manufacturing Process

August 10th, 2010

Manufacturers of plastic prototypes make use of big machines to produce prototypes of different shapes and sizes. Plastic molds can be created from a variety of different molding compounds such as silicone, latex or foam rubber molding compound. Knowing how to make plastic molds is a useful skill for model makers, or any person interested in making novelty items. Plastic molds are great because they are inexpensive to make and can be used over and over again. The process of creating a plastic mold is relatively simple and doesn’t require much time or many materials.
Plastic Injection Molding Process
Injection molding is one of the main methods by which parts are manufactured from plastic. The first step in the injection molding process is to feed plastic pellets into the hopper, which then feeds the pellets into the barrel. The barrel is heated and contains a reciprocating screw or a ram injector. A reciprocating screw is typically found in machines that produce smaller parts. The reciprocating screw crushes the pellets, making it easier for the plastic to be liquefied. Toward the front of the barrel, the reciprocating screw propels the liquefied plastic forward, thereby injecting the plastic through a nozzle and into the empty mold. Unlike the barrel, the mold is kept cool to harden the plastic into the correct shape. The mold plates are held closed by a large plate (referred to as a movable platen). The movable platen is attached to a hydraulic piston, which puts pressure on the mold. Clamping the mold shut prevents plastic from leaking out, which would create deformities in the finished pieces.

Plastic Extrusion Molding Process
Extrusion molding is another method of manufacturing plastic components. Extrusion molding is very similar to injection molding and is used to make pipes, tubes, straws, hoses and other hollow pieces. Plastic resin is fed into a barrel where it is liquefied. A rotating screw propels the liquefied plastic into a mold, which contains a tube-shaped orifice. The size and shape of the tube determines the size and shape of the plastic piece. The liquefied plastic then cools and is fed through an extruder, which flattens the plastic and forms the piece into its final shape.
A number of complications can arise during the plastic manufacturing process, including burned parts, deformities, surface imperfections and brittle parts. Parts become burned when the molds are not kept cool or if the melting temperature in the barrel is too high. Additionally, if the reciprocating screw becomes jammed or is not rotating fast enough, liquefied resin will remain in the barrel too long and become scorched. Surface imperfections and deformities occur when the surface temperature of the mold is uneven, if the molds are not clamped tightly enough or if the melting temperature is too high. Brittle pieces are formed when not enough liquefied resin is injected into the mold or if the plastic hardens before the mold can be filled.

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Different Types of Metal Casting

August 9th, 2010

 Metal Casting is to put metal melting into the liquid with certain requirements and pouring the liquid into the mold, the solidification by cooling, clearing the entire treatment by a book shape, size and performance of the casting process.  Casting is one of the foundation of modern technology machinery manufacturing industry .there are many types of  Metal Casting.

Sand Casting
This type of metal casting involves making a mold in a sand mixture and then pouring liquid metal into the sand cavity. This is a simple six-part process: (1) Use a pre-existing pattern to create a sand mold, or craft one by hand. (2) Add your gating system (to control the liquid metal). (3) Remove the pattern.(4) Pour in the metal. (5) Cool. (6) Remove the casting. This is the best form of casting for a small operation that will be making castings in small batches.
A variant of this is shell molding. This is similar to sand casting, except with the added touch of using resin to hold the sand together. This requires a much longer lead time and requires the heating of the mold between castings, but it has the advantage of allowing castings to be turned out more rapidly.

Plaster Casting
Using plaster to make a mold has the advantage that a plaster mold is easy to make. If the mold is damaged in ejecting a metal casting, turning out a new one is a simple affair (often, a plaster mold is, in itself, a plaster casting). This method is used for metal alloys based on aluminium, zinc and copper  for the manufacture of lock components, fittings, gears, ornaments and valves.

Die Casting
This involves forcing molten metal into cavities under high pressure. First, the mold is lubricated and closed. Then liquid metal is shot into the die/mold under high pressure. The pressure must be sustained during the casting process. Finally, the die is opened and the shots (not casting; shots differ from castings since there may be multiple cavities in a die, yielding multiple castings per shot) are removed. This is an industrial process for producing a large number of small- or medium-sized pieces that must have a high quality of detail and consistent features. It is commonly encountered when a toy or part is “die-cast.”

Permanent Mold Casting
This is what most people think of when they imagine casting. Two halves of a mold are joined, and liquid metal is poured into the mold through a hole in the top. The metal is allowed to cool, and the casting is struck by separating the two halves of the mold. Old-fashioned bullet casting is done this way.

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Types of Plastic Molding

August 6th, 2010

Plastics are available in two main types: thermoplastics and thermosets. Thermoplastics are meltable, but thermosets are not. The difference is in how their polymers are formed. Polymers, or chains of atoms, in thermoplastics are like one-dimensional strings, and if they are melted, they can be reshaped. Thermosets are three-dimensional chains that always keep their shape. A variety of processes are used to shape or mold plastic, some that can make only thermoplastics or thermosets and others that can make both.
Extrusion
The extrusion molding process begins with raw plastic such as pellets, powder or beads. A hopper feeds the plastic into a revolving chamber. The chamber, called an extruder, turns and melts the plastic. The melted plastic is forced out of a die and becomes the shape of the finished product. The item is dropped onto a conveyer belt, where it is cooled with water, cut and finished. Items Products made by extrusion include sheets, film and pipes.
Injection Molding
Injection molding uses the same principle as extrusion. The raw plastic is fed from a hopper to a melting chamber. However, instead of being forced out of a die, the melted plastic is forced into a cold mold under high pressure. Once the mold cools and solidifies, the product is cleaned and finished. Products made by injection molding include butter containers, bottle caps, toys and lawn furniture.
Blow Molding
Blow molding is a process that uses a blowing method after extrusion or injection molding. Extrusion blowing uses a die that creates a heated plastic tube with a chilled mold around it. Compressed air is blown through the tube to force the plastic to conform to the shape of the inside of the tube. This allows manufactures to create a continuous, uniformly melted, hollow shape without having to attach separate injection-molded parts. Injection blowing still uses an injection mold, but instead of a finished product, the mold is an intermediate form that is heated to be blown into a final shape in a different cold mold.
Compression Molding
Compression molding is the process of taking a pre-specified volume of plastic material, putting it into a mold, and then using another mold to flatten or compress the plastic into the previous mold. The process can be automated or manual, and it can use either thermoplastics or thermosets.

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carbon composite mold design

August 6th, 2010

A mold assembly or system includes a moldbase that holds mold inserts and has embedded fluid lines to facilitate cooling during part formation. Mold inserts combine to form mold cavities that receive carbon fiber and resin components to form a carbon composite based part. A permanent release coating along a mold component surface that contacts the carbon fiber and resin components facilitates the release of the finished part from the mold component.

Guide pins and guide pin receiving holes facilitate accurate alignment of mold components. Ejector pins within respective ejector pin shafts help eject a finished part from a respective mold component. An ejector pin shaft cover transfers force from an ejector pin to eject a finished part and also prevents substantial passage of resin into the ejector pin shaft. A fluid actuated ejection system provides fluid based mechanical forces to the ejector pins to facilitate finished part ejection.

“Composite molding generally involves molding a combination of different materials, each having a particular mechanical strength in a different direction, to form a final product that has mechanical strengths in multiple directions. Many popular forms of composite molding involve the use of carbon fibers or another similar component and a resin material, the molded combination of which results in a relatively strong part or component, particularly with respect to the weight of the part. Generally, fibers and resin are placed over or into a mold and are then cured under increased heat and pressure. Fibers typically come in sheet form, which can include “prepreg” or resin impregnated sheets, and are often layered into the mold sheet by sheet. Such a layering process is often performed manually by an operator, as are other steps in a typical composite molding of a part.

“Because resins tend to stick to mold surfaces, removal of a finished part from a mold can be a tricky process that often also involves manual intervention by an operator. Despite the application of a temporary release coating to inner mold surfaces prior to placing in the composite materials, the removal of a finished part from a composite mold still can involve prying and peeling the part away from the inner mold surfaces. Surface defects and blemishes on composite molded parts often occur as a part of the molding and mold removal process, which results in many parts having unique defects or appearances.

“Further, temperature discrepancies from molded part to molded part using traditional composite molding processes can also result in blemishes or defects that are different for each part. Due to these particular examples and other concerns that relate to composite molding, many composite molding processes are highly manual labor intensive by nature, and often result in the formation of parts that are not fully consistent from part to part.

“This is unfortunate in that many manufacturers might desire the mass production of consistent parts that have the strength of carbon composite components. As but one example, it would be particularly helpful if portable electronic device housings and components could be stronger and more durable than what is now typically provided in plastic parts that are formed via ordinary plastic injection molding processes. In particular, it would be beneficial if laptops, notebook computers, and other relatively large and heavy portable computing devices could have outer housings that are better able to protect the entire device from drops and other mechanical shocks.

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Challenges in Blow Mold Design(2)

December 31st, 2009

Tags:Plastic blowing mold making Industrial mold making Thread mold making

Blow Mold Design and Build Requirements Al Vanover, V.P. of Marketing at Mid-America Machining (Brooklyn, MI)!aa producer of blow molds, trim tooling andother related tooling!astate that depending upon the technology and machine platform, the mold has certaindynamics, which means there must be a minimum obligation on the machinery manufacturer to accommodate.

A mold of a certain size needs to hve a sufficient platen size and clamp force to allow the mold to functionproperly, Vanover elaborates. With w machinery technology and different means of blowing a container, thereare always explorations on how to blow the container faster, exhaust the air and cool the flash, which is themoldmakers!? challenge today.

With higher cavitation machiery and sometimes faster cycletime requirements, we cannot lose sight of those key attributes that make !(R)a good mold a great machine,!?!±continues. !°In the competitive blow moldmaking environmet, we believe value-added is the best ingredient tosuccess. Whether it is the cooling design, the cavity layout, the mold materials or the proprietary technology thatexists, the design process continues to evolve with almost everyproject.Wilmington Machinerys high-sped, small bottle (SB) rotaryblow molding wheel system uses a miniaturized version of thecompany!?s mechanical clampng systems!aa technologyoriginally perfected in their larger wheel machines!acombinedwith a proven technique for accurately positioning the clampsand molds relative to each other.

Newman points out that this new technology was developedbecause traditional methods were not yielding productiveresults. !°Some blow moldingmachinery manufacturers havebegun promoting tandem blow!athe process of blow molding twobottles per parison that have been configured in a neck-to-neckor base-to-base arrangement in the mold,!± Newman states.

Their rationale is not necessaril that this technique producesbetter bottles, but that it is the only way to increase output without incurring the additional cost of multiplemachines.

However, producing two identical bottles in a tandem blo process is a problematic challenge, especially with freefalling parisons typically used by shuttle and reciprocating blow molding machines,! Newman continues. Theparison shape is never identical from the top to bottom in the mold; and achieving an identical material distributionin the top and bottom containers can be next to impossible. Additional variation is added by trying to balance andset up four, six, eight or more parisons to be identical. Even with wheel machines the physical variations in bottlesblown in a tandem process can never be totally eliminated.!The new machines system uses a singleparison and individual cavities, instead of tandem, in order to produce thehighest quality bottles with the least variation in material distribution bottle-to-bottle, and with the smallest weightvariation.

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Automation boosts injection moulding quality (3)

December 6th, 2009

Tags:Mold Maker Plastic Mold Maker Plastic Injection Molding

Robots and gripper components on-line Delivery at extremely short notice is becoming an increasingly important factor in the automation field.

With a view to shortening delivery times, Engel is currently planning an Internet Ordering System which will ensure the fastest possible delivery of robots and gripper components to customers in any part of the world.

By the middle of this year, Engel’s website will feature an On-line Shop offering an assortment of robots available at short notice, especially the most commonly used types.

The website will also feature a catalogue of the complete range of modular gripper components – “GRIP TOOLS” – which will enable customers to put together their own individual gripper system and then order it on-line.

This service will prove ideal, for example, in cases where processors have to change over from one product to another at very short notice and require a new gripper system immediately.

The advantages to the customer: extremely short delivery times for the most commonly used types (two to three weeks), simplest possible ordering procedure and fast response (e-mailed quotations for customized equipment within max.

two working days), constantly updated overview of readily available robots, and selection and immediate ordering of gripper components from the on-line catalogue, enabling conversion or retrofitment within the shortest possible time.

Engel automation technology means customer benefit – for years to come For multi-colour or multi-component injection moulding systems, automation of the production process is a technical necessity in many respects.

If, for example, parts are to be moulded in four different colours, or from four different materials, and the four moulding processes are to be shared betwee

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Mold Making Tutorial

December 4th, 2009

Mold Making Overview:

A good clean mold is a sculptor’s best friend. If you are a sculptor and plan to make money as a sculptor then you need to learn how to create molds. When you have the ability to create molds, you have the ability to create multiple copies of your creations. Once you have your mold you also have the ability (and flexibility) to reproduce your sculptures in many different ways. You can cast your sculpt in plaster, stone, plastic, wax (for bronze copy’s), resin’s, and many more materials for a huge variety of applications. In this tutorial I’ll be molding my little troll sculpt that I created for the Sculpting Tutorial. My troll was sculpted in 3 separate pieces (body, left arm, and right arm) so that they can be molded separately and assembled later. I’ll be molding this sculpt in silicone (GI-1000, my favorite molding silicone). One thing that I’d like to stress most of all is- it’s very important to create clean neat molds. Sloppy molds will work sometimes, but they will never last.

GI-1000:
There are many mold making rubbers and silicones to choose from but for many years GI-1000 (A Silicones, Inc. product) has remained as the standard for silicone mold making. I worked in the movie industry for a special effects company for 5 years and GI-1000 was the most used molding material. It has great flexibility and tear strength, and also a very low shrinkage rate. GI-1000 is not the cheapest silicone but molds made from it will last you a long time, so in the long run it is the cheaper solution. Anyway, I just thought I’d bring this up because I know how confusing it can be selecting your product when there are so many options out there (No, I do not have stock in the company).

Before You Begin:
Before you start on your mold it is very important to select where your parting line will be. We’re making a 2 piece mold here, and we need to decide where the seam for that mold will be. The 2 pieces of the mold should be able to open and close as cleanly as possible and the seam should be as straight and level as possible. Think about how you will be casting materials into the mold and the best orientation for casting into the mold. You need to find the best place for your pour spout and watch for places that might catch air bubbles. Sometimes this will be a no brainer, but other times you will need to be very careful about where you place your parting line. This will become second nature to you with experience, and you will start planning for molds before you even start your sculpture.

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ComposiMold, Reusable Mold Making Compound

December 2nd, 2009

Make more Unique Molds with 1 pound of ComposiMold than you can make with 20 pounds of other mold making materials.

ComposiMold is a flexible, rubbery, molding material that can be melted poured and reused. This material is a thermoplastic mold making material that is great for small mold parts using many different casting materials including plaster, cement, epoxy, and polyurethane.

ComposiMold can be used for molds, mold making, and as a resin. Here are some Examples of a molded saki cup, little puppy, and others.

ComposiMold works by melting, molding, casting, and re-using. See Using ComposiMold to read more about how to use ComposiMold.

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Explosive Growth Prediced for Injection Molded Wood-Plastic Composites

December 2nd, 2009

The injection molded wood-plastic composites (WPC) market is embryonic in its stage of development. Only in the past few years has the market started to develop, primarily as an outgrowth of the success found in the wood-plastic composites extrusion market.

This emerging business provides an outstanding opportunity for over 10,000+ injection molders in North America. Projected demand for injection molded wood-plastic composites will experience 70% average annual growth to reach a market size of over $350 million in 2008. Building products will be a critical market to fuel growth although packaging, lawn & garden, and houseware applications will also contribute significantly to the overall market demand.

Jim Morton, Senior Partner, says, “There are two main replacement opportunity platforms for molders to pursue: natural materials and unfilled/filled plastics in traditional plastics markets. The exciting news is that molders can find new sources of revenue growth that do not cannibalize existing sales of molded plastics. In fact, nearly two-thirds of the potential addressable market is based on targeting the replacement of natural materials like wood, stone, and slate, among others.”

It is relatively easy for injection molders to move from traditional plastic injection molding to WPC injection molding. Limited capital investment is needed due to minor equipment and tooling modifications required. However, some key processing hurdles that molders must closely monitor include thermal sensitivity, moisture sensitivity, and shear sensitivity of WPC formulations compared to traditional filled plastics. In addition, tool design, product design limitations, and consistency in fabricated parts are also concerns in adopting these materials.

Principia’s newly completed study entitled INJECTION MOLDING: OPPORTUNITIES IN NATURAL & WOOD PLASTIC COMPOSITES 2004 provides a detailed market assessment for building products, automotive, infrastructure, industrial, and consumer markets in North America. It also includes estimates of current and future demand for dozens of applications as well as technology developments, competitive materials and profiles of leading molders, equipment producers, and merchant compounders.

This new report is prepared by consultants from Principia’s professional staff who have monitored the business development activities in the dynamic and growing wood-plastic composites industry since the early 1990s. Principia Partners is an international business consulting firm serving the building products, plastics, packaging, metals, and specialty chemicals industries.

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Plastic Injection Molding Firm Recaptures Business from China

November 17th, 2009

For years many businesses turned to cheap labor markets, such as China, for inexpensive manufacturing solutions, but premier plastic injection molding company C&J Industries has noticed a reversal in this trend.

MEADVILLE, PA – Pennsylvania-based plastic injection molding company C&J Industries recently announced that it has noticed a reversal in the trend of firms outsourcing manufacturing to cheaper labor markets, such as China. In fact, ten percent of C&J Industries’ current business includes projects that were transferred back to the United States from Chinese manufacturers. Specifically, the firm has observed a significant amount of medical, consumer and industrial related business being pulled from Asian markets.

“In today’s uncertain economic conditions, there is something attractive about doing business with integrity – it is not a given anymore. Businesses were choosing to go over to China because a ‘herd’ mentality was driving many manufacturers there-but now some companies are coming back,” says Mark Fuhrman, Marketing Manager for C&J Industries.

As an overall trend, some original equipment manufacturers are bringing projects back from China due to problems with communication, continuity of supply, logistics as well as total overall cost. C&J Industries’ guiding principles are very attractive to these frustrated companies.

Through higher cavitation molds and automation, C&J Industries is often able to provide a lower cost option than some Chinese manufacturers. Ingenuity and innovative technology are driving forces behind C&J Industries’ competitive advantage. The firm’s success can be attributed to its overall commitment to quality and willingness to invest in capital to better serve its customers.

Additionally, C&J Industries’ superior warranty surpasses any available through Chinese manufacturers. In the plastics industry, when a custom injection molder builds a tool, they typically offer a standard warranty based on the number of shots or cycles, similar to a standard three year, 36,000 mile warranty on a car. However, C&J Industries goes beyond standard by offering a 10-year warranty on production tooling.

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