Injection Molding Services: How They’re Used in the Automotive Industry

Injection molding service are used in a variety of industries to create custom parts and components. In the automotive industry, injection molded parts are used in everything from dashboards and door panels to airbags and engine blocks. In this blog post, we will take a closer look at how injection molding is used in the automotive industry and explore some of the benefits these services offer.

The History of Automotive Plastic Injection Molding

auto injection molding

Injection molding is a manufacturing process that dates back to the 19th century. In 1872, John Wesley Hyatt patented the first injection molding machine, which was designed to create celluloid billiard balls. In the early 1900s, Leo Hendrick Baekeland invented Bakelite, the first synthetic plastic. Bakelite was used to create a variety of products, including radios, telephones, and electrical insulators. In the 1930s, Bakelite was replaced by synthetic rubber and polystyrene.

During World War II, plastic injection molding process was used to create a variety of items, including gas masks and helmet liners. In the 1950s, plastics became increasingly popular in the automotive industry. In 1953, Ford Motor Company introduced the first car with a plastic body: the Ford Crestline Skyliner. In 1955, General Motors released the Chevrolet Bel Air, which featured a plastic grille and bumper.

The Benefits of Automotive Plastic Injection Molding

Automotive Plastic Injection Molding

There are many benefits that injection molding services offers the automotive industry. Injection molded parts are strong and durable, and they can withstand a variety of harsh conditions. In addition, these parts are resistant to corrosion and chemicals. Injection molded parts are also lightweight, which helps to improve fuel efficiency.

In addition, plastic injection molding is a cost-effective way to produce large quantities of parts. Injection molding is also a highly versatile manufacturing process, and it can be used to create a wide variety of shapes and sizes.

Here are a few reasons why the process is good for the production of Automotive injection molding parts:

  • High Volume Production

  • Cost-effective

  • Reduce The Weight

  • Tin,

  • Iron,

  • Silicon.

High Volume Production

Injection molding is a highly repeatable process, which means that parts can be identical in size, shape, and strength. Automotive injection molding services have high repetition accuracy, mainly manifested in the small weight deviation of parts; weight deviation is usually below 0.7%.


Injection molding is a cost-effective way to produce large quantities of parts. However, the injection mold manufacturing process can be expensive. However, this is still highly scalable, with overall costs falling as manufacturers make more parts. For mass production applications, injection molding is therefore beneficial to manufacturers.

Reduce The Weight:

The biggest advantage of applying plastics in automotive materials is reducing the weight of the car body. Lightweight is the goal of the car industry, and plastics can play a big role in that. General plastic specific gravity is 0.9~1.5, fiber reinforced composite specific gravity will not exceed 2, and metal materials, A3 steel specific gravity is 7.6, 8.4 for brass, aluminum 2.7. This makes plastic the preferred material for lightweight vehicles.

Easy Forming

Injection molding servcies including: insert molding, overmolding and prototyping. It is very convenient to process parts with complex shapes. For example, the instrument panel is processed with a steel plate, which often needs to be processed into various parts first, and then assembled or welded with connecting parts. And the use of plastic can be molded, the processing time is short, and precision is guaranteed.

High Precision

Injection molding can achieve very tight tolerances and produce parts with a high degree of surface finish. In addition, the process can produce highly complex shapes that would be difficult or impossible to create using other manufacturing processes.

Strong Corrosion Resistance

Plastic corrosion resistance and local damage will not corrode. And the steel production, once the paint damage or the antisepsis is not good, is easy to rust corrosion. The corrosion resistance of plastic to acid, alkali, and salt is greater than steel plates. If plastic is used as a body cover, it is suitable for use in areas with large pollution.

Increased Security

The elastic deformation characteristics of automobile plastic products can absorb many collisions, have a great buffer effect on strong impact, and protect the vehicle and passengers. Modern cars use plasticized dashboards and steering wheels to enhance shock cushioning. The left and right bumpers and body trim strips are made of plastic to reduce the impact of objects outside the car.

Color Options:

The color of the plastic product is determined by adding a pigment to the resin during the production process. To meet customer requirements, some manufacturers have developed more than 100 kinds of color masterbatches. 

Commonly molded plastics & Applications for Automotive Injection Molding Industry

molded plastic automotive parts

In the automotive industry, injection molding is used to create a wide variety of parts and components; The following are the application of different plastics in the automobile industry:

General-Purpose Plastics


Polypropylene, commonly known as 100-fold rubber, is similar to white waxy, transparent, light quality, injection molding fluidity is good, and water absorption is less than 0.02%. The shrinkage of PP is 1.0-3.5%, and the appropriate thickness is 1.5-2.5mm.

PP Applications in Automotive Injection Molding

There are many automotive products made of PP resin; there are all kinds of instrument panelsdoor guard platescolumn guard platesbumperswater tanksand decorative plates; PP in the application of the car has more and more trends.


PE Automotive Plastic Injection Molding

Polyethylene, white wax material, good water resistance, acid and alkali resistance, organic solvent resistance, and excellent electrical insulation. Shrinkage rate 1.5 ~ 4.0%, suitable thickness 1.0-2.5mm.

PE Applications in Automotive Injection Molding

Automotive products manufactured by PE mainly include the fuel tankair ductfront seat decorative coverair duct assembly (HDPE), left and right ventilation pipe assemblyupper and lower wind blade connection barleft and right foot vent assembly, etc.


automotive plastic injection molding services

Polyvinyl chloride, commonly used as PVC, is a multi-component plastic; because the content of each component is different, it forms a variety of mechanical properties of different hardness of PVC particles, generally divided into soft PVC and hard PVC two categories. 

PVC Applications in Automotive Injection Molding

Polyvinyl chloride is the most commonly used plastic raw material in automotive products. Automotive plastic products made of PVC plastic can be seen everywhere, such as PVC instrument panel skin, PVC plastic steering wheelPVC plastic lining board, and PVC plastic car floor materials. This is not only because PVC resin is price economical, but processing and comprehensive mechanical properties are better.


Polystyrene with good fluidity and no water absorption. Due to the fragility of PS, it is often grafted and copolymerized with other substances, such as HIPS grafted and copolymerized with butadiene. Shrinkage rate 0.4-0.7%, appropriate thickness 2-3mm.

PS Applications in Automotive Injection Molding

PS in the car’s main application in the instrument shelllampshadeand lighting products.

Polystyrene can also be prepared by foaming molding packaging materials and thermal insulation materials, used for the production of ceilings, and is with other materials graft copolymerization and modification, get a lot of fixed collocation of PS family of alloy plastic varieties, such as SMA used in the manufacture of automotive dashboard skeleton.


ABS automotive injection parts

Acrylonitrile – butadiene – styrene copolymer, commonly known as super unbroken glue, the body is white. 

ABS Applications in Automotive Injection Molding

Due to the variety of ABS, good surface treatment effect, and low price, it is widely used in the automotive field. Because of the poor weather resistance of ABS, high weather resistance AES, ASA, and other materials have been widely used in commercial vehicles to supplement ABS.

When the product needs surface treatment (such as water transfer film or spraying), use ABS; ASA and AES are used when surface treatment is not required. The most typical automotive products are decorative glittershift handle headinside open handlelicense plate decoration platerear spoiler assemblyrear view mirror bodyradiator grid body, armrest, and so on.

General-Purpose Plastics

Engineering plastics, because of their better comprehensive mechanical properties, in the field of automotive, are also widely used; this paper mainly introduces polyamide (PA), polymethacrylate (PMMA), polyformaldehyde (POM), polyamide (PU), polycarbonate (PC).


Polyamide, commonly known as nylon, industrial use of PA more kinds, commonly used PA6, PA66, and PA610. It is necessary to pay attention to the size change of moisture absorption after forming. The water absorption rate of 100%, relative moisture absorption saturation can absorb 8%, and suitable wall thickness: is 2 ~ 3.5mm.

PA Applications in Automotive Injection Molding

PA in the automotive field is mainly used in the manufacture of hose (brake hose, fuel pipe), combustion oil filterair filteroil filterpump housingpump impellerfanbrake fluid tankpower steering fluid tankwhite leaf windowheadlight housingseat belt.


PS automotive injection molding

Polymethacrylate, commonly known as organic glass, outdoor aging resistance, excellent light transmission suitable plastic products: transparent structure with certain strength requirements.

PMMA Applications in Automotive Injection Molding

PMMA is widely used in automotive lighting signs, door glass, and lamp glass covers because of its good light transmission performance.


Polyformaldehyde, commonly known as plastic steel, has a shrinkage rate of 2-3.5% suitable wall thickness: 1.5-2.5mm.

POM Applications in Automotive Injection Molding

POM in the automobile with the manufacture of instrument panel glove box accessoriesall kinds of valves (drainage valve, air conditioner valve, etc.), all kinds of impeller (water pump impeller, heater impeller, oil pump wheel, etc.), all kinds of electrical switches and electrical instruments on the pinion, all kinds of the handle and door pin, etc.


injection molding automotive parts

Polycarbonate, with outstanding impact toughness and creep resistance, good heat resistance, and cold resistance, is also good. PC added to glass fiber can improve its shrinkage, mechanical strength, and temperature resistance; at 100℃ or so, long-term use of steel will increase and can be annealed to improve the internal stress.

PC Applications in Automotive Injection Molding

PC in the automotive field is mainly used to manufacture lampshadesleft and right wheel cover platesinstrument baffle body (PC+ABS), left and right wind frame coversmiddle wind frame cover (PC+ABS), and rear bumper cushions.


Polyurethane, according to the different polymerization products, is commonly used in hard and soft polyurethane.

PU Applications in Automotive Injection Molding

Polyurethane foam is widely used in automobile interior decoration, and vibration absorption parts, such as coating materials, polyurethane rigid plastic boardpolyurethane elastomer, soft foam materials for seats, decorative partssofa leatherand roof ornaments; The most used is a variety of soft and hard polyurethane foam materials, it has vibration isolation, sound insulation, noise reduction, heat insulation;

PU can also be made into vehicle polyurethane coatings, adhesives, sealants, etc. PU representative parts on the car include the instrument panelrearview mirrorbumper, seat cushionheadreststeering wheelinstrument panel anti-vibration cushionpillar trim, front top liningwindow frameceiling and side top frame decorationdoor lining panelsun visorrear top frame decoration, etc.

How to reduce the cost of auto injection molding prototypes?

Injection molding is not the only way to create prototypes of auto parts. Depending on the size, complexity, and quantity of the parts needed, there are a number of different methods that can be used to create prototypes. Some of these other methods include CNC machining, SLA/SLS, vacuum casting/resin casting, sheet metal fabrication/welding, and extrusion molding. Injection molding is just one of many options available to create prototypes of auto parts. Talk to a prototype specialist to find out which method is best for your project.

On the other hand, manufacturers can sometimes replace molded plastic parts with 3D-printed plastic car parts. This happens especially in prototyping, where there is less need for extreme durability or smooth surface finish. Many mouldable plastics can be used as filaments for FDM 3D printers or as powders for SLS 3D printers for nylon. Some professional and high-temperature 3D printers can also print reinforced composites for high-strength parts.

Why choose Automotive Plastic Injection Molding Services By Aria

Aria Manufacturing Limited is a full-service Chinese company that provides high-quality plastic injection molding services to the automotive industries. Our main office is in Dongguan, Guangdong.

Our injection molding capabilities include insert molding, overmolding, and mold making. We custom injection molding services include rapid delivery of prototypes, on demand production parts,high volume injection molding orders and low-volume injection molding project.

Our team of experienced engineers and technicians use the latest technology and equipment to design and manufacture high quality molded parts parts and components that meet the specific requirements of our clients. We pride ourselves on our ability to provide cost-effective solutions that meet the highest quality and safety standards.


Q: What Are Some of the Most Common Injection Molding Materials Used in the Automotive Industry?

A: Some of the most common injection molding materials used in the automotive industry include polypropylene, polycarbonate, and ABS. These materials are chosen for their durability, strength, and resistance to chemicals and heat.

Q: How Can I Get an Automotive Injection Molding Quote?

A: To get an automotive injection molding quote, please click here. Our team of experienced engineers and technicians will be happy to provide you with a quote based on your specific requirements. We pride ourselves on our ability to provide cost-effective solutions that meet the highest quality and safety standards.

Q: Injection molding automotive VS CNC Machining automotive, What is difference?

A: CNC machining is a process that removes material from a workpiece to create complex shapes and detailed features. Injection molding is a manufacturing process that involves injecting molten material into a mold to create various shapes and sizes of parts. Injection molding is a more efficient process than CNC machining, and it can be used to create parts with more intricate designs. In addition, injection molding is typically less expensive than CNC machining.


Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.