Month: February 2022

What are the plastic molding techniques?

The molding of plastic materials is the set of all those technologies which, thanks to the use of a diy plastic injection molding machine. It allows the production of components in polymeric material. Over the years and with the development of increasingly advanced technologies. The types of molding have differentiated according to the:

• Material to process
• The shapes to obtain
• The physical characterization that the final product must assume

The techniques that are most widespread today are the following:

Compression molding: rubber vulcanization process

It essentially consists of the rubber vulcanization process. The mold that gives it its final shape is in steel or aluminum. Depending on the shape of the product to produce. It is easy to make up of several parts in order to facilitate its removal when the molding completes.

The diy plastic injection molding machine for this type of molding is a press on which the mold fix to the working surface.

The working pressure varies from a few tens to about 850 tons. The worktop thermally control: in relation to the elastomer being processed. The electrically heated surface works at a temperature between 140 and 180 degrees. This type of molding is very flexible because it allows inserts of various kinds to incorporate into the product.

Polymer injection molding: an industrial process

It is an industrial process in which the plastic material heats and melts under high pressure into a closed mold. It will then open when the material has solidified.

Both the injection pressures and the temperatures of the material in diy plastic injection molding machine being processed are very high. This to allow easier sliding of the plastic material in the ducts of the machinery and in the mold itself. The machinery dedicated to this process is the so-called injection press which comes up of two main parts: the injection group and the closing group.

The first has the function of bringing the material to the melting temperature and, once plasticized, of pushing it into the mold. The closing unit, with hydraulic or mechanical operation, ensures the clamping of the mold.

Diy plastic injection molding machine with reaction

Injection and reaction molding, also known as RIM, Reaction Injection Molding. It is a process that uses polyurethane compounds for the production of large-sized products. Originally, its development dates back to the 1950s, it was mainly common in the automotive industry.

 This technique involves the use of two components in the liquid state before transfer into the mold: the Iso fraction, which contains isocyanates, and the Poli fraction, which contains hydroxyls.

The dedicated machinery comes with an aluminum mold inside which the polymerization and solidification of the material takes place. The modern technology that the diy plastic injection molding machine come with allows the creation of objects of all sizes.

Thermoforming: use of vacuum or pressure plates or films

This molding technique starts from vacuum or pressure plates or films. In the first case, the preheated sheet adheres to the mold by suction, assuming all its surface sensuosities.

In the second case, the sheet rests on the sheet due to the pressure applied with air which also speeds up its cooling. Thermoforming is particularly suitable. If the quantity of pieces to produce is large and production times are short and even if the batches to produce are different.

Machine is very versatile and flexible

By its very nature, a diy plastic injection molding machine is very versatile and guarantees a very high production flexibility especially if the thickness of the pieces is very thin. Generally, this machine is common for food-grade trays, blisters, Abs trays but also for internal cases of household appliances and finishes in the automotive sector such as panels and coatings.

Blow molding for a hollow shape

Blow molding is a technique common to give the plastic material a hollow shape. The most classic examples of this variant of plastic molding are produced as bottles, flasks and containers with very small opening compared to the other sizes.

Blow molding obtains with a jet of powerful compressed air blown into a preform in such a way that the worked object inflates and takes the shape of the mold that contains it. Once cooled, the object extracts from the mold and the processing complete. Machines for this type of molding usually equips with an extruder to make the preform.

Diy plastic injection molding machine for important dimensions

Rotational molding or rotational molding, is the molding technique common for the production of hollow products of important dimensions. The process consists of introducing plastic powder into a hollow mold which is then rotated on two axes.

At the same time, the mold heats to melt the material and make it adhere evenly to the walls. The mold is usually built with a composite material such as aluminum.

As in the other cases, cooling and extraction of the finished product, which is often manual, follow. The typical products of roto moldings are vases, bins, boats, furniture and toys.

Diy plastic injection molding machine for molding plastic materials:

Plastic material molding machines are sophisticated and highly technological equipment. Buying new ones often coincides with an excessively demanding economic effort for every type of company, whether it is opening or relaunching. Second hand is a viable solution, as long as it is efficient and guaranteed machinery.

In these cases, the unknowns are numerous and critical, difficult to dispel with only a basic competence of the subject. Most of the time it's like buying a pig in a poke and the game isn't worth the candle. The savings on the purchase can cause unpleasant inconveniences even in the short term.

When buying common machinery becomes a problem

On the web, there is no shortage of offers for diy plastic injection molding machine for plastic molding. Some affordable and reliable, others cheaper and often of low quality. Bankruptcy auctions of industrial machinery and plants are a solution to the problem. In all likelihood, the best.

The prices with which you can get a fully functional and well-maintained machine unmatched, neither on the Web nor in the traditional market. Industrial Discount is a platform that manages bankruptcy auctions of industrial machinery on behalf of the competent Court.

How to make soft plastic lure molds? Before building any artificial in plastic resin, we will have to worry about building around it to be reproduced, a two-part mold.

There are two main construction methodologies

The original to be reproduced could be an already existing artificial on the market or a new subject built by us, perhaps using balsa wood.

How to make soft plastic lure molds?

I use 3- or 4-mm plywood for the longer sides and 10 mm plywood for the two shorter sides. In this way we will be able to reuse them, without having to redo them every time.

We take our original, fix it or stick to it at both ends (head and tail), two steel wires. We can keep it raised halfway inside the plywood box.

Obviously, to do this, it will be necessary to make two cuts in the shorter sides of the box with the jigsaw up to approximately half height. How to make soft plastic lure molds? This operation will serve to create a small space (7/8 mm.) We will then pour the expensive silicone rubber. The remaining space of the box will be entirely occupied by the much cheaper plaster.

Method A: create a cylindrical or conical housing

Now we need to create a cylindrical or conical housing. This starts from the head of our lure and reaches the end of the mold. It will be good to use to pour the silicone rubber into the cavity left free by the plasticine.

Use a piece of nylon on the piece of marble

We then place the wooden box, with all its contents, on a work surface (I use a piece of marble) to prevent any spillage. How to make soft plastic lure molds? This keeps the empty part upwards. I recommend placing a piece of nylon on the piece of marble so that it can then be removed easily.

Quickly mix gypsum with water, in sufficient quantity to fill it, taking care to make a very liquid amalgam. It can easily fill every gap. The plaster sets in about fifteen minutes. We will have to act quickly, helping ourselves by cutting a small trowel to fill every smallest hole.

After about ten minutes, when the plaster has set, we will take a wooden (or marble) ruler. How to make soft plastic lure molds? With sharp edges about twenty centimeters long and, scraping slowly. We remove the excess plaster, above the box, leveling the surface until the sides of the wood emerge.

Now, we will allow the plaster to dry perfectly, for at least two or three days. It dries, small cracks form around the sides of the wooden walls and the plaster takes its natural white color.

 

Overturn plaster and begin to remove the plasticine

Now some space has formed again, the space necessary for the second plaster casting.

Before carrying out it, however, it will be necessary to sprinkle the surface of the dried plaster with a veil of detaching wax. We gently open the wooden box, and separate the two parts of plaster.

How to make soft plastic lure molds? Remove the plasticine

We have thus built two overlapping parts, two gypsum shells. This overlap will form the rigid reinforcement of our mold. Now we will sprinkle the artificial cleaned from the plasticine with a layer of release wax. We will prepare for the pouring of the silicone rubber for molds.

Join the two plaster parts with the help of ropes or rubber bands

We carefully close each slot with plasticine, with gummed paper or pieces of nylon. So as not to let the liquid rubber come out and we straighten the mold joined in plaster. How to make soft plastic lure molds? It holds the tube or the plastic cone, in order to facilitate the insertion of the liquid silicone rubber.

We catalyze rubber:

We will have to mix it for a long time with the tip of a large screwdriver, together with the necessary amount of catalyst.

The one I use requires 10% (ten percent) of catalyst and solidifies in 24 - 36 hours depending on the external temperature. For a mold of a medium / large size minnows, we will need 100 grams of silicone rubber and 10 grams of catalyst.

Pour the liquid through the plastic tube

How to make soft plastic lure molds? Now we can pour the liquid and catalyzed silicone rubber, through the plastic tube, until all the empty space around the lure and the tube itself are filled. But be careful to slowly pour the rubber, with the help of a small jug with spout, so as to let the silicone rubber flow slowly into the mold, in order to allow the air to flow towards the other, leaving the place to the rubber.

In this way the rubber will fill exactly the amount of space between the plaster and the original, allowing us to obtain a perfect mold.

How to make soft plastic lure molds? Rubber that manages to reproduce

Once the rubber has poured, the mold will be kept facing upwards, for the entire time necessary for its definitive solidification.

Now we can open our plaster mold, freeing it from the windings, we cut delicately with the blade of a sharp cutter, laterally the rubber, near the head, for about two / three centimeters on each side, in order to allow the original to extract.

Then we will continue the cutting operation, always following the contours of the plaster molds.

How to make soft plastic lure molds? Now we will detach the two parts of the mold; it is a very exciting moment, the moment of truth, because it is right now that we discover whether the steps of our upstream work have been correctly carried out.

Accommodate the plastic resin and the lure assembly

Having removed the original wood and cut the silicone rubber in two parts, one realizes with pleasure that the mold is finished, ready to accommodate the plastic resin and the lure assembly and to produce hundreds of baits ... super captivating.

At the end of the operation we will find two gypsum shells integrated with two parts of silicone; together they will form the mold to reproduce our lures.

Now the two-part mold is really finished

After drying, with a sharp cutter it will divide into two parts and the mold will be ready for use. How to make soft plastic lure molds? The same procedure will have to adopt if we have to reproduce Jigs or spinner bait heads and any other small parts.

In this case we will have to use inert sinking fillers (marble powder). It is to mix with the plastic resin. Moreover, it is to ensure that these details do not float, but rather cause the artificial for which they are intended to sink. We must be able to obtain at least 1 kg of silicone rubber for elastic molds and the relative catalyst.

General working principle of plastic injection machine

How plastic injection molding works? The basic plastic injection molding machine structure has shown the functions of each part working together. These parts operate on a common working principle.

Raw plastic (Plastic) is put into the material storage compartment through a hopper. The plastic granules in the cavity melt by a heater. We keep it in a liquid state until it enters the mold cavity.

The process of injecting plastic into the mold is similar to using a needle. The motor generates force on the helical screw. The screw operates in a clockwise direction creating a large pressure that pushes the plastic to the valve.

What is injection mold clamping system?

The mold clamping system has the role of fixing the mold under the impact of huge pressure. And the cooling system will quickly cool the product to push it out of the mold to continue a new press.

How plastic injection molding works? All presses have a central operating system that controls the entire operation of the machine.

Detail working principle of Horizontal plastic injection machine

Horizontal plastic injection molding machine is one of the most advanced presses available today. This machine originates from Japan.

The improvements of plastic injection machine bring positivity in production. Productivity and quality of pressed products are guaranteed, diverse and durable.

Plastic injection molding machine has various sizes for large molds and small molds. However, the size difference is relevant to the working principle of the horizontal plastic injection molding machine.

The working principle of the plastic injection molding machine

As learned about the plastic injection machine in detail in the structure and general operating principle of the above content, basically, the JSW machine is nothing else. It also works on the same principle: “Heating – injection molding – cooling – ejecting the product from the mold”.

 

How plastic injection molding works?  Injection molding machine is the most important machinery equipment common in plastic injection processing. In this article, we take a closer look at the structure of the injection molding machine and the parameters of plastic injection molding.

Details of injection molding machine structure

In general, an ordinary injection molding machine consists of 5 systems:

• injection molding support system
• Furthermore, injection system
• Moreover,  clamping system
• Mold system and control system.

Injection molding support system

How plastic injection molding works? The injection molding support system consists of 4 subsystems, each with its own function.

Body: is the part that has the function of linking the systems of the plastic injection machine together

Electrical system: includes electrical cabinets and wires, providing power, helping the motor to operate. The electrical system needs to be scientifically designed. Moreover, it helps to ensure the safety of the operator.

Hydraulic system: composes of pump, valve, and pipe system, motor... is the place to generate resources for closing and opening the mold.

The cooling system comes with the function of cooling the mold by water or Ethylene Glycol solution. In addition, it helps the plastic material to harden into the desired shape before ejection. Moreover, it solidifies the plastic into a shape before the product is ejected from the mold.

Spray system of injection molding machine

The injection system melts the plastic material under the influence of temperature, maintains the temperature of the liquefied plastic, compresses and degass it during the injection of the plastic into the mold cavity as well as the shaping of the product.

The injection system comes of a:

• plastic feed hopper
• Moreover, a plastic container
• Similarly, heating rings
• a screw
• Furthermore, a nozzle and a self-opening return unit

How plastic injection molding works? During operation, when the screw moves backward, the wedge-shaped barrier moves towards the nozzle. The molten plastic will flow in front of the screw head. The screw moves forward, vice versa.

Clamping system

Clamping system with mold opening and closing function helps to hold the mold firmly while waiting for cooling and opens to push the product out of the mold.

The clamping system is composed of the pusher assembly, the clamp assembly, the connecting rods, the movable plate and the fixed plate.

Plastic Injection Mold system

The mold system is a plastic product forming injection molding system consisting of a fixed half and a movable half. In which, the fixed part carries the mold cavity (female mold) and the movable part carries the mold core (male mold).

How plastic injection molding works? The mold system with a very complex structure, basically includes the following components:

Guide and positioning system: including guide pin, guide bearing, positioner, positioning ring...

The system of leading plastic into the mold cavity: including the nozzle silver, plastic channel, nozzle...

Product pushing system: including push pin, return pin, support pin, support pin bearing, push plate, retaining plate, support block...

Cooling system: including water lines, grooves, heat pipes, connectors (hollow shaft pipes, faucets)...

Plastic Injection Molding Exhaust system:

The control system is the operating system of the injection molding machine. Injection molding parameters such as temperature, pressure, injection molding speed, position of hydraulic system parts clearly display on the control panel.

How plastic injection molding works? The control system is the basis for the injection molding machine to perform operations during the entire pressing cycle.

Parameters of injection molding

Different types of plastic injection molding machines will have different injection molding processing parameters. Some common features in the parameters that the plastic injection machine operator should understand include:

Spray speed

The injection speed has a direct impact on the shape, determining the characteristic properties of the product. It is necessary to set the standard injection molding speed based on the characteristics of the plastic injection machine and the plastic product you want to form.

If the pressing speed is too high, it will make the product not aesthetically pleasing, glossy, surface blurred or seam floating...

If the injection molding speed is too low, it will cause the mold not to be filled, causing lack of material, shrinkage, deformation, and failure to meet the required size standards.

Injection pressure

How plastic injection molding works? Just like injection molding speed, injection pressure has an effect on the operation of the injection molding machine and on the characteristics of the formed product.

If the injection molding pressure k adjusts reasonably, it will affect the quality and aesthetics of the formed product. Usually, high injection pressure is common in the production of parts that require thin walls and high pressure is common in the case of thick product walls.

Press area of injection molding

Products with different technical requirements require different injection molding areas. The pressing area clearly defines and the setting is reasonable during the whole injection molding process.

Injection area is an injection molding machine parameter that can affect the clamping force, mold size and technical parameters of the plastic injection machine.

How does plastic injection molding work? To design a complete set of plastic injection molds, the Mold Design Engineer must understand the structure of the plastic injection mold. Depending on the product requirements, we will have different mold structures such as: 2-plate mold, 3-plate mold, slide mold.

In the brochures Mold analysis a lot, in the sky and under the sea of ​​knowledge, if you study and very time consuming & unnecessary practice. So I share the most necessary knowledge for you to make molds.

1. Plastic injection mold construction.

Structural decomposition of the mold set

More or less you already know that Mold includes core and cavity (male mold, female mold). In addition, there are many other parts in the mold. These parts are assembled together to form the basic systems of the mold set, including:

How does plastic injection molding work? The system of guidance and positioning: includes all the guide pins, guide bearings, core positioning, mold shell positioning, etc., which are responsible for keeping the working position of the two mold parts when coupled together to create the cavity of the mold exactly.

How does plastic injection molding work?

The system of leading plastic into the mold cavity: includes the nozzle silver, the plastic channel and the injection port responsible for supplying plastic from the injection machine nozzle into the mold cavity.

Slide system (sliding platform): including side cores, core cheeks, guide bars, oblique cams, hydraulic cylinders, etc., which are responsible for removing the parts that cannot be removed (undercut) right in the direction of the mold opening.

Product ejection system: includes push pins, return pins, support pins, support pins, push plates, retaining plates, support blocks, etc., which are responsible for pushing the product out of the mold after pressing is complete. How does plastic injection molding work?

Exhaust system: consists of air vents, the exhaust valve is responsible for bringing out the remaining air in the mold cavity, creating conditions for the plastic to fill the mold cavity easily and keeping the product free of air bubbles or air bubbles burnt, lack of materials.

Cooling system: includes water lines, grooves, heat pipes, connectors, etc., which is responsible for regulating the mold temperature and cooling the product quickly. There is also a heating system to keep the mold temperature stable at high temperatures for products using engineering plastics.

Hot runner system: The hot runner system is also known as the hot channel system. ( Read more articles about Hot runner system design )

Bolts - nuts: Common to fix mold plates, components in the mold together...

18 basic parts in plastic injection mold structure

Structure of the basic plastic injection mold set.

1: Front clamp plate 7: Support plate 13: Pin guide silver

2: Front mold plate 8: Support block 14: Pause

3: Positioning ring 9: Rear clamp plate 15: Silver Expansion

4: Silver spray stem 10: Push pin 16: Support pins

5: Products 11: Holder plate 17: Rear mold plate

6: Locator 12: Push plate 18: Silver guide

How does plastic injection molding work? Depending on the shape and requirements of the product, we will choose different types of mold structure. Each production unit also follows different mold design directions. However, in order to improve the design level, the designer needs to learn to improve by studying as many mold structures as possible.

If you have the opportunity, you should open the actual molds to study and expand your design thinking.

Functions of components in the plastic mold

1. Front clamp plate:

The function is common to clamp to the fixed part of the machine wall. As you can see in the picture, this plate has a protruding width compared to other mold plates. That protrusion is common for clamping.

2. Fixed plate (female mold plate):

This plate is the fixed mold part

3. Silver sprayer:

The function of leading plastic from the injection head of the injection machine into the mold (first is to lead the plastic into the channels)

4. Positioning ring:

 

Common to position the mold with the machine wall, it helps the nozzle of the press to be accurately positioned with the corresponding position of the nozzle bush. This part has a circular shape and protrudes above the top of the front clamp to fit into a corresponding hole in the machine wall.

5. Hexagonal screw in Plastic injection Molding Machine:

Fix clamp plate and fixed mold plate together

6. Water line:

It is cooling system of the mold. It also has the function of keeping the mold temperature during the heating process for low-melting plastics.

7. Movable plate (male mold plate):

Movable side mold plate

8. Backing plate:

Common to increase the rigidity of the movable side mold, this plate is only common in case the movable plate is too thin.

9. Pillows:

How does plastic injection molding work? Pillows consisting of 2 panels on both sides are called a pair. The support is common to support the movable plate and create the necessary clearance in the middle to arrange the push pin clamp and push plate and the battery system.

10. Battery clamp plate:

Keeps the push pin system from sliding out during mold operation

11. Pin ejection plate:

This plate connects to the ejector core of the press; it has the function of pushing the push pin system through which indirectly pushes the product out.

12. Rear clamp plate:

Common to clamp on the movable part of the injection molding machine

13. Push pin:

Common to push the product out of the mold

14. Loxo:

Push the clamp plate assembly and ejector plate backwards to pull the ejector battery pack to prepare for the next injection molding cycle

 

15. Return latch:

How does plastic injection molding work? It guides the clamp and ejector plate assembly in a reciprocating straight line to keep them from sliding out and to protect the battery pack from bending during product ejection and retraction.

16. Guide Bearing:

Precision machined with guide pin makes the guide pin easy to move and position

17. Guide pin:

Helps the 2 parts of the mold to be precisely positioned during the molding process