Create a concept map of the Injection molding process. Include at least 5 links and 3 sub links for each link (i.e., 5 topics and 5 subtopics). Two of the links must be 1) defects and 2) Materials, the other three are up to you. Worth 8 points

There is no input to several process of the modeling like, Raw material, Machine, Electricity, Manpower, Heat Furnace as well as they also have their own sub links as shown in the below figure. The output side it could be different product of difference industries, defects, wastage, as well as other also shown

Part 2. Mould design.

In a 1-page report discuss materials used to make moulds, the number of cavities used to make moulds (report how many and what determine the number of cavities), and describe the procedure to fabricate moulds.

Worth 10 points.

Materials used to make moulds

Among the famous materials for mould, some of the important ones are silicone rummer, epoxy, alginates, ceramic supplies, polyurethane, natural latex, liquid latex, alginates, and urethane rubber. The common materials for the cast making process are concrete, plaster of Paris, metals, waxes, Gypsum cement, and plastics (epoxies and resins). Most often the mould making materials are the manmade rubber and natural rubber because of their ability and flexibility to reproduce the extraordinary materials. some of the mols are developed by using rigid materials including gypsum plasters.

Number of cavities to make moulds

In the plastic injection molding process, there are a different number of items that can be moulded in one shot by using the process known as the number of cavities. The number of cavities in the moulds can range from 1 to a reported maximum number of moulds of 216. The total number of items that are moulded in one shot becomes large by increasing the number of cavities. This method reduces the production cost per item. By increasing the number of cavities in the moulds the trend of quality fluctuation increases with variation in external appearance, weight, dimensions, and other moulded items. The general trend shows that the number of cavities in the mould depends on the type of mould. It is highly important to determine the number of activities that are small and large upon the comprehensive understanding of advantages and disadvantages.

What determines the number of cavities?

In the table below, the trend is mentioned about the number of cavities depending on the type of mould.

The number of cavities in the moulds depends on the mould construction, technical factors, economic factors, cycle time, quantity to be moulded at one cycle, mould making cost and unit price (Acomold. com, 2020). There are few considerations to be considered when deciding the number of the cavity and these points are listed below,

1.      Delivery time

2.      Quality and tolerance

3.      Melt flow and layout

4.      Injection machine capacity

The process to fabricate moulds

The methods for the fabrication of moulds are different on the basis of the type of material and the number of cavities in the moulds. The variety of mould types with their applications are discussed below,

1.      The pour moulds are composed of pour silicon over the original inside of the box.

2.      1 part pour mould is a black mould that uses only one side fabrication.

3.      2 part pour mould is composed of two halves and the keys of these parts are aligned with each other.

4.      The brush on mould is composed of the material that is brushed after making it. it is brushed with a thin layer of silicon that build up a simple skin or layer to encase the rigid mould with structure while casting.

Part 3. Polymers for injection molding. Worth 10 points.

Discuss that the difference is between polymers and plastics, investigate 2 polymers that can be used in injection molding. Write 1-page report for each polymer.

The information you are asked to investigate is:

· Recommended processing parameters (temperature, pressure, etc.)

· How the polymer is made?

· Properties of the polymer

· Processing Conditions

· Typical defects

· Typical trouble shooting for defects while processing

· Common products made of this polymer

· Advantage/disadvantage of this polymer.

*remember everything is related to injection molding process.

Difference between polymers and plastic

It can be noted that the polymers are defined as a long-chain compound that is made up of small repeating units named as a monomer. On the other hand, plastic is considered as semi-organic material derived from petroleum. The next point is that polymers are made up of small monomer units and these plastics are made up for a long chain of polymers. According to the structure, polymers contain a monomer structure and plastic is containing a polymeric structure. The two main types of polymers are addition and condensation polymer. Moreover, the main types of plastic are thermoplastic and thermocouple plastic. The key difference is that plastic is a type of polymers (Goodship, 2004).

2 polymers used for injection moulding

The two main polymers that are used in injection moulding is a type of thermoplastic. They include polycarbonate and polyethene (Goodship, 2004).

Processing parameters of polymers

There are some processing parameters of polymers used for injection moulding. The main purpose of these processing parameters is to plan DoE during injection moulding. Some important processing parameters are used for injection moulding. These parameters include cycle time, cooling time, fill time, injection speed, holding pressure, mould temperature and injection pressure. These parameters are important because they are required to optimize finished plastic product with high-quality efficiency. Some important researches have been made for optimizing the process of injection moulding and produce a high-quality product. Moreover, these process parameters are also carried out for minimizing short shots. if during injection moulding the operator can control these processing parameters then it will become easy to produce a quality product. According to the fact, the injection pressure will be about 125 bar, mould closing speed will be about 200 mm/s, mould pressure is about 90 bar, and backpressure is 15 bar then maximum results will be obtained (D.V. Rosato, 2012).

How the polymer is made

It can be noted that the synthetic polymers are made through the chemical reaction named as polymerization. Moreover, this process has occurred in different forms. But the main fact is that this process has consisted of repetitive chemical bonding of the monomers or small individual molecules. The next thing is that there is also use of heat, pressure and a catalyst. This is because all of these parameters will help the polymers to alter the chemical bond and also properly hold them. Through this, it can easily form a strong bond with each other.  Due to this bonding of the molecule, they are forming a long linear chain of molecules named as polymers. This is who such structures are formed (Goodship, 2004).

Processing conditions of polymers

In the given table below there is complete information about the processing conditions used for injection moulding. These conditions are extremely necessary because through this it will become easy to create a quality plastic product with the help of injection moulding.

(Goodship, 2004)

Typical defects during injection moulding

There are some typical defects are occurred during the injection moulding process. From them, the first one is related to the flow lines. It appears when there is no constant injection speed. The next one is related to the burn marks. These marks appear on the surface or edge of the moulded part. The next defect is warping and it is a deformation and it occurs in different injection moulded products after shrinking of different parts, another defect is related to the vacuum void. Such air pockets are formed in the finished moulded product. Furthermore, there is another typical defect in injection moulding and it is related to sink marks, they have occurred in the form of depression or small recesses. They have mostly occurred when the inner part of the plastic completely shrinks. The next type of defect is related to weld lines. It is the most common defect in injection moulding. It has occurred only when molten material has quite low coverage after splitting off into two important part. It is almost a hire like and may lower the material bonding. Another defect is related to discolouration and it is also called as colour streaking. It has occurred only when a moulded part contains a different colour (D.V. Rosato, 2012).

Typical troubleshooting for defect while processing

It can be noted that there is a need for an optimal process setting to improve the production process. This shows that typical troubleshooting is extremely easy for the company during injection moulding. For improving the fine lines during injection moulding, there is a need to increase the injection speed, material temperature and pressure. Moreover, relocate mould gates properly and maintain distance between them. Also, increase the nozzle diameter so it will also to stop early cooling. The burn marks can be controlled easily by lowering the meld and mould temperature properly, decreasing the injection speed and also decrease the mould cycle time in a proper way (D.V. Rosato, 2012).

Products made from injection moulding

Different products are made from injection moulding. These products are given below

·         Plastic bottles

·         Toys

·         Electronic housing

·         Agricultural items

·         Household materials

·         Pipes

·         Instruments for the healthcare industry

Advantage and disadvantage of injection moulding

The advantages and disadvantages of injection moulding are given below

Advantages: It will provide efficient precision. This is why it is considered perfect for the intricate parts.

·         The next advantage is that it provided high repeatability. It will become easy to made products overtime again and again.

·         This process is also extremely cost-efficient

·         It is also considered a fast process for the industry. This is because its cycle time is less than 10 seconds.

Disadvantages: There is a high initial cost of moulding.

·         Moreover, the initial lead time is extremely high. This shows that from the product concept it will take a lot of time for designing,

·         It is not able to make large parts

·         For making products there is a need for a careful design otherwise it will create issues (D.V. Rosato, 2012).

References of Advantage and disadvantage of injection moulding

Acomold. com. (2020). How to determine the Number of Cavity in a Mold? Retrieved from www.acomold.com: http://www.acomold.com/how-to-determine-the-number-of-cavity-in-a-mold.html

Artmolds. com. (2020). Mold Making Materials. Retrieved from www.artmolds.com: https://www.artmolds.com/molding-materials.html

D.V. Rosato, M. G. (2012). Injection Molding Handbook. Springer Science & Business Media.

Goodship, V. (2004). Practical Guide to Injection Moulding. iSmithers Rapra Publishing.

Kuban, G. J. (2012). Common Mold and Cast Making Materials. Retrieved from paleo.cc: https://paleo.cc/casting/material.htm

Misumi-techcentral. com. (2011). #096 On the Number of Cavities in a Mold. Retrieved from misumi-techcentral.com: https://www.misumi-techcentral.com/tt/en/mold/2011/10/096-on-the-number-of-cavities-in-a-mold.html