The primary molding process mainly used in the plastic industry is injection molding.
With the help of the injection molding machine and the influence of heat, the plastic material is brought to a viscous state.
Subsequently, the melt is injected under pressure into the cavity in the mold.
The shape and surface structure is determined by the geometry of the cavity.
Cooling or cross-linking reaction (for elastomers) solidifies the part and it can be ejected after opening the two mold halves.

The injection molding process is particularly suitable for large quantities.
This is due to the fact of high mold costs which need to be payed proportionally by the produced parts.
Injection molded parts can be used directly after ejection.

The pressure at different positions inside the cavity/runner is called “Pressure Distribution”.
Ideally in injection molding process, the pressure distribution should be uniform throughout the cavity after the molten plastic completely fills the cavity. In this case the molded part shrinks uniformly.
In reality due to the different cooling behaviour of the part there is always a difference in pressure distribution.

Injection molding simulation is a great tool to predict the pressure inside the cavity, which can help to achieve uniform pressure distribution as good as possible.

The pressure of the melt pushes the mold to open due to a too low clamp force.
On the parting line, the mold opens a little and the outcoming melt freezes and a flash remains.
The risk of the flash formation can be reduced by the use of a machine with a higher clamp force or the reduction of the specific pressure in the cavity.
Another reason for flash formation can be the wrong positioning of the touching surfaces at the parting line.

No further melt can enter the cavity of the injection mold after the smallest diameter of the cold runner freezes off.
This duration is called freeze time and represents the theoretically maximum packing time.
While increasing the packing time stepwise it is possible to find out the freeze time by taking the weight of the parts. As soon as the weight stays the same, the cold runner is frozen.
In the simulation the freeze temperature in this area or the flow rate help additionally.

The pressure inside the cavity is called cavity pressure. It is usually smaller than the specific pressure due to pressure losses.
Sensors inside the mold are used to measure the cavity pressure and to compare it with the injection molding simulation.
The time-pressure curve of a complete cycle helps to validate the vp-switch, as well as the effect of the packing phase.
The part quality can be evaluated easier.

The injection mold is usually temperated during the complete cycle.
The time from the end of packing phase until ejection is called residual cooling time (blue line in the time-pressure diagram below).
During this time the cooling of the part takes place solely.

Depending on the variation of density between processing and ambient temperature in injection molding shrinkage might appear.
Shrinkage is divided into two fields: processing and post processing shrinkage.
Processing shrinkage occurs in the mold due to volumetric contraction, mold restrains, crystallinity and orientation.
Post processing shrinkage is measured usually after 24 to 48 hours after the production.
Shrinkage happens mainly due to the relaxation of residual stresses.

To compensate the shrinkage, it is necessary to inject more material after 100% filling of the part.
The length of packing time (green line in the time-pressure diagram below ) must be selected in such a way that the gate freeze time is reached.
A short packing time leads to a higher risk of sink marks and voids.
Similar things will happen, if there is still molten material within the part but the gate is already frozen.

In injection molding, part inserts are commonly used to produce parts.
First, the part inserts are added into the cavity, after that the melt over molds it on one side.
This is why the process is called "Overmolding".
The advantage of this process is that the materials are connected due to the hot melt by a strong bond.
Gluing of the different parts is unnecessary in this case.
This process is often used with films as part inserts.
It is important to control the process temperatures since a melting of the insert is not or only partially wanted.

In areas with thick walls and across from ribs, a hollow at the surface might appear.
Sometimes a difference in the gloss to the surrounding surface might be noticed only.
Mass accumulation leads to a higher volumetric shrinkage, which is insufficiently reached by packing pressure.
The surface is pulled to the inside during cooling and a sink mark appears.
Small wall thickness and higher packing pressure in the critical area reduce the risk of sink marks.

A group of experts in the plastic industry founded the company PLEXPERT, 2006 in Germany, in order to save resources, providing a positive impact on budget and environment.
There are two divisions within the company. One is focusing on finite element simulations (FEM) like injection molding simulation and structural analysis.
Based on decades of practical experience DFM conform results are given by the consultant service of PLEXPERT to decrease part costs and increase quality in the production of plastic parts.
The second division is focused on the development and supply of soft- and hardware to the plastic industry. With the state of the art products PLEXPERT contributes to secure production and reduce the need of precious resources.
Today PLEXPERT has offices in Canada, Germany, Thailand and China in order to support its customers fast and effectively.
Due to a close network of plastic experts, partners are available in many other countries as well and offer PLEXPERT products and services.

The space between the two mold halves, which should be filled with melt, is called cavity.
The shrinkage of the material needs to be considered for the production of the cavity to get dimensionally accurate parts.
In the injection molding simulation, it is important to use the cavity size for the warpage calculation.

In areas with thick walls and across from ribs, a "hole" in the inside might appear.
Mass accumulation leads to a higher volumetric shrinkage, which is not insufficiently adjusted by packing pressure.
The melt is pulled to the surface during cooling, that a hollow remains in the inside.
CT-Scan and cutting the part help to detect these errors.
Small wall thickness and higher packing pressure in the critical area reduce the risk of voids.

"Parts, which have been produced from melt by non-cutting molding (e.g. by pressing, compression molding or injection molding) in all side closed molds" are referred
to as molded parts according to DIN 7708, sheet 1 [freely translated].
Thus in injection molding, the end product, which is produced by filling the cavity with molten plastic, is called a molded part.
It should be noted that a possibly existing cold runner is not a component of the molded part.

Handling of parts, mounting elements or modifying existing parts can be done by an industrial robot. It is a machine that can be programmed and used universally according to changing requirements.
In injection molding, industrial robots are used with five or six movable axis.
Their diversity tasks range from the removal of parts out of the cavity up to palatalizing and assembly work.
The increased flexibility compared to standard linear handling units leads to a wide spread of industrial robots in injection molding.
Modern designs feature additional sensors in order to allow the robot to decide what to do in specific situations.
In the best case, a direct cooperation between human and robot (collaborative robot) becomes possible.

In injection molding, two different materials (also known as components) are frequently used to produce one part.
The materials can be completely different (hard and soft polymers) or have the same base but with different color.
In the 2 Shot Molding process, the first component is injected into the cavity and cooled down up to a certain point.
Afterwards, the first component is transported, for example, by a rotating dish tool or a robot, to a new cavity to inject the second component on top of it.
It is important to consider the different processing temperatures.
The remelting of the first component is not wanted.
At the same time, both components should stick together.

In two shot molding, the first component is commonly robust and gives the shape of the geometry.
Therefore, it is also called the hard component.
Its rigidity leads to the main influence for the warpage.
Typically, its materials are PP, PS or PC+ABS.

In the plastic industry, different materials (components) are used frequently to create parts with more functionality.
For example:
Components with a different material (e.g. metal) are inserted into the mold before injection molding.
This is done manually or with a robot.
It is important to hold the insert in the correct position until the plastic flows around and fixes the part.
The encapsulation allows a strong connection between insert and part, and both will be ejected as one.

is a tolerance specification and is found on engineering drawings to describe the position of the center of a bore or surface.
The toleranced straight line or plane must lie between two planes that are perpendicular to the reference with the set distance.
For bore centers, the axis of a bore must be inside a cylinder of the given diameter.
The cylinder axis must therefore coincide with the location of the bore axes to the given reference planes.
There are special cases where a point can be set as a toleranced element (e.g. center of a sphere).

Even when the mold halves are exactly centered on top of each other, core shift might happen.
Especially long, thin cores are pushed away due to unbalanced filling.
The unbalanced injection of the melt leads to a one-sided pressure on the core.
The movement results in changing wall thickness in the part.
In the area of reduced wall thickness, the filling is more difficult than in the are with higher wall thickness.
Weaknesses, given by to the changed wall thickness, lead to problems during the usage of the part.
A balanced flow around the core and a hold on both sides of it helps to reduce the risk of core shift.

For the production of injection molded parts a mold is necessary to be placed on the injection molding machine.
It is commonly build out of steel or aluminum and is designed as a permanent form.
Depending on the plastic material used millions of parts can be created with one mold.
The complexity of a mold range from a simple two-plate molds up to a complex stack mold with sliders, etc.
To avoid additional costs it is important to think about the mold concept early in the concept phase of part design.

By processing regrind via a melting process (Compounding) and adding additives compound (regenerate) is obtained.
The additives are used for example to specifically define the mechanical properties of the material.
The Regenerate (Compound) has, like the regranulate, a uniform particle size and no dust content.
Therefore the material can easily be reused for the production of injection moulding components.

A process in which fine powdered material with high melting point (>1.000°C) is mixed with thermoplastic based binders to a moldable compound is called powder injection molding.
The powdered material comes preferred wise in globular shape and corn sizes of 15 µm – 20 µm. The binder is incapsulating the powdered corn.
Volumetric share: Binder > 20 % / powdered material < 80 %. This mixture or recipe is called Feedstock. The PIM-process is a multiple stage process, whereas plastic injection molding is used as first manufacturing process. The debinding process is the second process step, where the binder material is removed. Third step is the sintering process. With sintering, the remaining material is melted at the outer surface and creating a compact part with densities of 99,95 % and higher against virgin compact material (e.g.: solid block of forged steel). Mechanical and other material properties of final part are mostly comparable to full solid materials. This process is preferred wise used in mid-/ high volume applications designed with average up to high complexity. PIM is very cost competitive against standard multi stage cutting technologies like milling, drilling, grinding, etc. Best practice examples for PIM-processes: Stainless steel watch-housings, ceramic grinders, power-wash nozzles, medical devices and many others.

If an integration of electronic, optical and mechanical functions is realized in one part, the part is called MID part.
MID is short for the term Molded Interconnected Device. In a newer description, MID is also referred to Mechatronic Integrated Device.
When it comes to injection molding, a part is produced using a thermoplast with additives. With this, the optical and mechanical properties are defined.
After the production, there is a second step (e.g. using the LDS process) in order to activate the additives. This is important to allow metallisation of the part in a third step.
The metallisation is used to create the circuit lines in order to prepare the base for mounting SMD elements for completing the electrical function of an MID part.
Besides this, the MID technology is widely used in creating antenna for mobile communication.

Metal Injection Molding is A PIM-process in which fine-powdered metal is mixed with a thermoplastic plastic binder material to a Compound is called metal injection molding. The fine-powdered metals are the feedstock. This feedstock can be processed with plastic injection molding. The plastic injection molding process allows competitive manufacturing of mid to high volumes and mid to high complex part designs.
In a second process step, the molded part is debindered – the thermoplastic binder is removed from the feedstock.
In a third process step, the debindered part is sintered.

Densities of 99,95 % and higher against compact virgin material can be obtained.
Material- and mechanical properties of final processed parts are mostly comparable to the corresponding compact, solid materials.
MIM is very cost competitive against standard multi stage cutting technologies like milling, drilling, grinding, etc.
Best practice examples for MIM-processes: Stainless steel watch-housings, aerospace, textile industry, medical applications and many others.

A powder injection molding (PIM) process in which fine-powdered ceramic is mixed with a thermoplastic binder material to a moldable compound is called ceramic injection molding (CIM). This fine-powdered ceramic builds the so called feedstock. This feedstock can be processed with plastic injection molding. The plastic injection molding process allows competitive manufacturing of mid to high volumes and complexity in repeatable quality.
The molded part is debindered in a second process step. The thermoplastic binder material is removed from the compound.
In a third process step, the debindered part is sintered.

Densities of 99,95 % and higher can be obtained against compact material. Material and mechanical properties of final parts are comparable to the corresponding compact materials.
CIM is very cost competitive against standard multi stage cutting technologies like milling, drilling and grinding.
Best practice examples for CIM-processes: Ceramic grinders, textile industry, medical applications and many others.

Linear or branched chain structures, which consist of repeating monomers are called thermoplast (also known as thermoplastic).
They can be softened and re-hardened infinite times.
Reheating temperature should not exceed a material specific maximum, as it will cause degradation of the polymers.
Typical examples of thermoplastic materials include PA, PE, PC and PVC.
Thermoplastics can be subdivided into two distinct classes: Semi-crystalline and Amorphous.

This term refers to an auxiliary substance used in plastics processing to prevent a molded part from adhering to the surface of the mold. By applying this substance to the mold surfaces, the demolding of plastic parts becomes easier and the risk of damage or surface defects is reduced. Such agents are particularly used in processes such as injection molding, compression molding, or laminating. They can be applied as a spray, liquid, or solid coating and form a thin separating layer between the mold and the plastic material. This supports a reliable and consistent demolding process.

To get the parts homogeneously and with as least as possible tension out of the cavity, ejectors are used.
Additional ejectors can be set as optimization for the venting system.
The ejectors are mainly axial pins, which are located on the ejector plate and fixed from the ejector holding plate.
The movement of the ejector plate takes place most of the time by hydraulic.
When moving forward, the pins press against the parts and throw them out. The backwards movement is done by hydraulic or spring force.
The movement of the ejectors has a big influence on the wear of the mold.