ABS Injection Molding

If today all the wisdom of ABS injection molding were lost, the very pillars of civilization could crumble. Since the 1950s, Acrylonitrile Butadiene Styrene (ABS) has played an important role in the manufacture of consumer goods, electronics, medical products, and so much more, delivering incomparable strength and cost efficiency. In 2023, LEGO made over 80% of its products with ABS.  

Nearly similar levels of high ABS demand and usage can be traced across Samsung, Ford, Dyson, and Medtronic. Electronics and consumer goods are clearly the biggest drivers of ABS injection molding. The material itself is very cost-effective, but the injection molding process takes it a notch higher in terms of speed, cost-efficiency, and scalability.

What is ABS Injection Molding?

ABS injection molding refers to the mass production of parts and finished goods using melted ABS resins injected at high pressure and temperatures onto a pre-designed metallic mold. This is a high-precision process. Injection molding solves many of the headaches of manufacturing. Studies show that by adjusting key parameters in the process, such as mold temperature and holding pressure, manufacturers can achieve optimal levels of:

• Dimensional accuracy (minimal risks of internal cracking)
• Process repeatability and time efficiency
• Scalability and cost savings ( through economies of scale)

ABS is a good candidate for injection molding because it flows easily when melted. Its low viscosity is a great cost saver because it improves cavity filling and subsequently, the dimensional accuracy of parts. The material cools predictably well between 40 and 80 degrees Celsius. ABS parts do not lose their shape or unique geometrical properties when cooled.

Brands like Nintendo and Sony have reaped the benefits of ABS injection molding, including getting products shipped faster and at a fraction of the cost of other materials. Nintendo Switch and Sony PlayStation 5 outer casings are produced via ABS injection molding. The end user benefits in many ways, including product durability, impact resistance, and scratch resistance.

ABS Material Properties

ABS is a compilation of the monomers, namely acrylonitrile, butadiene, and styrene,  with each bringing unique properties to the whole.  These are impact strength, tensile strength, and rigidity, with a good amount of chemical resistance and moderate heat resistance.

• Acrylonitrile is known to survive exposures to harsh chemicals and heat without deforming. 
• Butane is synonymous with toughness, guaranteeing parts and products’ survival even when dropped or smashed.
• Styrene guarantees internal strength and an appealing outer surface finish

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Examples of ABS Properties in Industry

The reasons why many manufacturers, including auto makers and beauty product brands, choose ABS are strategic. For instance, Mercedes and BMW use ABS in interior components such as dashboards because it doesn’t crack. In the medical industry, patient monitoring device enclosures, nebulizers, and surgical instruments are made with ABS because of its strength and superior hygienic properties. The medical grades of ABS are easy to clean and are also biocompatible.

In beauty and cosmetics, packaging kits must withstand high impact when dropped or stored in environments where scratching or exposure to oils and chemicals is common.  ABS materials deliver the durability needed to survive these high-stress usage and storage conditions. However, beauty brands also benefit from the color stability of the material, which yields packaging parts with elegant finishes. Makeup kits, lids, mirrors, compact cases, and mascara tubes can be made with AB, as seen with Revlon, Aveda, and L’Oreal.

What Makes ABS a Superior Material?

A closer look at the properties of ABS material reveals surprising facts. There are many more thermoplastics whose advantageous properties blow the benefits of ABS out of the water. The only thing that makes ABS stand out is that it blends many beneficial properties in a single material, leading to holistic performance improvements in applications.

For example, the impact strength of ABS is 200-300 joules per meter. Although stronger than many thermoplastic options like Nylon and Polyethylene, it’s weaker than Polycarbonate. But unlike PC, ABS is much more affordable, has better flow characteristics, and produces parts with smooth finishes.

The same goes for tensile strength. ABS sits somewhere close to the top and compensates for what it lacks with its other superior properties. The tensile strength of ABS is 22-74 MPa, which is lower than Polycarbonate’s (72- 90 MPa) but higher than HDPE’s (15-45 MPa). However, ABS is more lightweight and its overall injection molding costs are lower.

At What Temperature Does ABS Become Pliable?

ABS melts at 170-190 degrees Celsius, but it’s injected at 200-240 degrees Celsius, depending on the grade. This temperature is optimal for maximum flow and faster cycle times and may contribute to lower manufacturing costs. The temperature level at which injection molding materials become soft and formable directly impacts success.

It can be seen that the moderately high pliability temperature of ABS plays a part in its performance in practical applications. ABS parts that survive high-temperature exposures.  ABS performs reliably in car dashboards where temperatures can get really high, to 80 degrees or higher. For applications that require even higher temperature resistance, such as aerospace, PEEK (Polyetheretherketon) is the preferred material.

Can ABS Plastic Be Considered Strong and Safe?

Yes. ABS is a reliable material with proven levels of safety if used in compliance with industry standards and governing regulations.

• Standard ABS parts comply with UL 94 HB, the basic level flame-resistance certification.
• Flame-resistant ABS grades (strengthened with chlorinated compounds) meet higher UL 94 V-O ratings for usage in electronic parts.
• FDA-compliant ABS grades (21 CFR 178.3297-compliant polymers) are safe for use in food packaging and refrigerator drawers. 
• ABS materials are child-safe (LEGO products have not been recalled since 2009), are easier to clean, and do not have harmful BPA and phthalates
• The mechanical safety of ABS is assured in its high impact resistance, high tensile strength, and good durability and dimensional stability.

However, the UV resistance levels of ABS are significantly lower compared to alternatives. Without a strategic additive, ABS parts become brittle, lose color, and can break down.  Therefore, outdoor tool brands such as Dewalt and Ryobi prefer polycarbonate for their tool casings for UV resistance and higher mechanical strength.

When Should You Consider ABS Plastic?

As we saw earlier, ABS uniquely balances cost-effectiveness, strength, rigid toughness, and aesthetics in ways that not many other resins can. If your application requires this hard-to-find balance of beneficial properties, then consider ABS. Its applications make sense for both startups and established manufacturers across a wide range of industries.

Use ABS in the production of parts that need to be lightweight and yet impact-resistant. Your products will be able to withstand shock without breaking, which translates to more lifetime value and customer satisfaction.

Choose ABS when manufacturing aesthetic consumer-facing products. ABS guarantees high-quality surface finishing, including smooth and glossy facades that require minimal polishing and painting.

General-purpose startups that want to extend their runway should consider ABS material because it’s cheaper. Very few other materials match the cost-effectiveness of ABS and its holistically blended mechanical qualities. Therefore, it’s beginner-friendly as it makes a small budget go further without sacrificing quality.

Use ABS for tight-tolerance applications where fit dictates success and failure. In custom applications, tiny deviations in product geometry can trigger performance and safety issues and sometimes costly product recalls. ABS saves the day with its low shrinkage rate and stable flow properties, which improve the dimensional accuracy of parts.

Other instances when the use of ABS makes the most sense include:

• When you need more ease of manufacturing, ABS is easy to process, so you can make a high volume of products fast and cheaply
• If you need to make parts with good electrical insulation, ABS has good insulating properties
• When you need additive-friendly resins, ABS plays well with additives that improve its strength, UV resistance, and temperature resistance.

How to Injection Mold ABS Plastic

ABS can be injection molded with electric, hybrid, or hydraulic injection molding machines. The first process for this material is drying because of its hygroscopic nature, which makes it absorb excess environmental moisture. Drying prevents cosmetic defects such as streaks in the final output.

Next, ABS pellets are melted in a barrel at high temperatures of 180-200 degrees Celsius into a molten state. The melted ABS is then injected into a preinstalled mold cavity at high pressures of about 150 MPa and left to cool. As the melted ABS cools, it assumes the shape and dimensions of the mold. After sufficient cooling is achieved, the part is ejected and moved to post-processing for polishing or painting.

ABS requires precise temperature control, and pressure must also be carefully monitored during injection molding. Small deviations from optimal molding and cooling temperatures and pressure result in cracking and warpage. 

The success of ABS injection molding and, by extension, its performance in IRL applications largely depends on the process efficiency. From part design to tooling and parameter control, many opportunities arise for engineers to make adjustments that improve output quality. 

ABS Injection Molding Design Tips

ABS injection molding objectives revolve around improving the manufacturability, structural integrity, and aesthetic quality of parts. These design goals are true regardless of product type or industry, and manufacturers can achieve them by:

• Maintaining uniform wall thickness to prevent warpage or shrinkage
• Using small to moderate draft angles between 1- 2 degrees for easier scratch-free ejection
• Reducing undercuts and other complex design features that drive up manufacturing costs
• Shortening cycle times by implementing high-performance cooling systems
• Reinforcing the part with ribs and inserts to increase structural strength
• Optimizing gate placement for better flow

Maintaining wall thickness is not optional. Without this, the material won’t fill the cavity, leading to inconsistent cooling and subsequently, warping.  Engineers can use mold flow simulations that make it easier to predict the best wall sizes for better flow and cooling.

As for optimal draft angles, the best practice is to add them early in the CAD design stage as opposed to later in production. This prevents warping and bending and guarantees a smoother surface finish for the ejected parts. Optimizing draft angles during the production cycle can lead to delays and costly redesigns.

Undercuts are useful only if the design makes them necessary. Otherwise, they drive up costs. The use of splitting-geometry redesign and large draft angles helps to eliminate the need for undercuts.

For shorter cycle times (and lower production costs), cooling systems must be installed around hotspots, e.g., where walls are thickest for maximum heat absorption. Thin-wall injection molding practices are helpful, too. But ensure wall thinning doesn’t sacrifice part strength and structural rigidity.

What Are the Pros and Cons of ABS Injection Molding?

Pros

• High impact resistance
• Affordable and lightweight
• More processing efficiency
• Supports complex geometries
• Can bechrome-platedd
• Maintains color stability

Cons

• Breaks down under high heat
• Poo UV resistance
• Moisture sensitivity

ABS vs Other Plastics

Table showing how ABS compares to other plastics

Property	ABS	Polycarbonate	Polypropylene	Nylon (PA6)	Polystyrene	Polyoxymethylene
Tensile Strength (MPa)	29 – 48	55 – 66	25 – 40	70 – 86	30 – 60	60 – 70
Heat Resistance (°C)	80 – 100	65- 75	82 – 135	150 -200	60 – 80	82- 105
Impact Strength (kJ/m²)	10 – 20	60 – 90	3 – 30	5 – 15	2- 15	5 – 25
Flexural modulus (MPa)	1,600 – 2,400	2,000 – 10,000	1,100 -1500	1,000 – 1,300	2,500 – 3,200	2,410 -3,100
Moisture Absorption (% by weight)	0.1 – 0.6	0.2 – 0.3	Under 0.03	1.4 – 10	0.3 – 15	0.2 – 0.8
Heat Deflection Temperature (°C under a load of 1.8 MPa)	88 – 100	130 – 180	60 – 70	60 – 255	70 – 100	105 – 120

What is the Difference Between ABS and PC Injection Molding?

PC injection molding is much more complex than ABS injection molding. While ABS requires moderate temperatures of 220-250 degrees Celsius, PC injection molding requires higher temperatures of 260-320 degrees Celsius.

ABS is easier to injection mold because it flows fast and easily at lower injection pressure. PC is a highly viscous material when melted and can cause critical challenges, demanding higher injection temperatures for comprehensive filling.

One other area of difference is the drying process before the melting and injection begin. ABS is a hygroscopic material that requires drying before melting.  But PC is even more hygroscopic, and that means it requires more drying time than ABS.

As you can expect, production cycle times for PC injection molding are longer than for ABS. Apart from longer dying time and a highly viscous nature that impacts flow time, PC requires longer cooling times. This often translates into higher energy usage and higher machine-hour costs that increase overall production costs.

What Are the Applications of ABS Injection Molding?

• Computer manufacturers use injection-molded ABS for laptop cases and monitor housings.
• Auto makers use ABS injection molding for interior trim and seat-back shells.
• Appliance manufacturers use ABS in refrigerator liners.
• Construction industry manufacturers use ABS in pipes and fittings.
• In the power tools industry, ABS is used for outer casings.
• In the consumer goods industry, ABS is a key component in toys, helmets, skateboards and blenders, and coffeemakers.

How to Overcome the Challenges in Injection Molding ABS?

Sink Marks

This is a cosmetic blemish that appears on the finished part as a result of delayed core cooling during rapid surface solidification. The use of strategically spaced-out cooling channels throughout the thick sections of the mold can help even out cooling. Sometimes, remedying sink marks also requires the use of ribs and gussets to maintain wall thickness uniformity and reduce the risk of shrinking.

Weld Lines

When separate melt flows in the mold meet but don’t fully fuse at the molecular level, the result is visible seams on the molded part. This is not just an aesthetic problem because these lines are a possible indicator of structural weakness along the points of convergence. The solutions to weld lines in ABS injection molding include using wider gates for optimal flow and using hot runners to maintain higher temperatures for complete molecular fusion.

Voids

Voids are the internal spaces within the molded ABS parts, and they are usually filled with trapped air. This problem occurs when sections of the part cool at different rates, with the outer surface cooling faster than the internal layers. The fix for voids in ABS injection molding is increasing the pressure and time of the injection process. This forces material to flow much more comprehensively and fill all cavities, eliminating air pockets.

Warpage

Internal stresses in the molded part, such as those resulting from uneven cooling, can cause distortion or bending in the molded part.  Engineers can prevent warpage during ABS injection molding by the strategic implementation of cooling channels. For instance, thicker sections require more rapid cooling, while thin spots should be designed for slower cooling.

Alternatives to ABS Injection Molding

Vacuum casting is a great alternative when production volume is under 500 units. However, vacuum-cast parts are not as durable as ABS parts, and silicone molds degrade just after a few cycles.

FDM 3D Printing is the most popular additive manufacturing alternative to ABS injection molding for fit-testing. However, a major caveat with 3D printed parts is layer-line fragility, which can compromise the impact resistance of parts by up to 50%.

CNC Machining is another promising ABS injection molding alternative. It is more suitable for the rapid production of prototypes without the need for molding. Its biggest advantage over injection molding is high precision results for parts that require tight tolerance levels. However, CNC machining is more expensive per part than injection molding.

Other less popular ABS parts manufacturing techniques include:

• Selective laser sintering
• Thermoforming
• Blow molding
• Stereolithography

How Much Does ABS Injection Molding Cost?

The total cost of ABS injection molding is a sum of the following different expenses incurred during production:

• Material costs per kg: $1.3 – $3.6
• Prototyping costs – $100 – $2500 per part
• Mold fabrication costs: $1000 to over $100,000, depending on cavities and tolerance levels
• Machine-hour costs:  $300- 700 per hour
• Labor fees:  $35 – $200 per hour

Also Read: How Much Does Custom Injection Molding Cost?

Let’s Build Your ABS Components Fast and Cost-Effectively

EzraMade has cut its teeth in speedy and cost-effective ABS injection molding, having delivered over 28 million parts to leading industry partners. Our processes are designed to improve output quality, accelerate delivery time, and reduce costs. 

We have no minimum order requirements, and our lead times are under two weeks for high-volume orders and 3 business days for prototypes.  We provide end-to-end support, including design assistance, 3D drawing optimization, and DFM review to guarantee the best results. 

Our transparent quotes and open lines of communication to the production floor give you peace of mind throughout the manufacturing process.

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Conclusion

ABS injection molding is a cost-effective and reliable means to meet the growing demand for ABS parts across industries. The benefit of ABS injection molding rests in the material’s properties and the ways it balances strength and cost effectiveness, and the scalability and speed of the process itself.  

The best ABS injection molding partners focus on better design and hybrid material grade selection to improve part performance in real-world applications.  Find out how EzraMade can elevate your next ABS injection molding process. Request a quote here.

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