Plastic Injection Molding Manufacturing FAQ

Injection molding products are used in a wide range of industries. They could be ABS caps, medical injectors, or UHMWPE armors.

How can you choose the right plastic injection molding manufacturer to make quality products for you at a competitive price?

First of all, you have to understand the functions and features of plastic products you need, and if the plastic injection molding company can help you understand more and define it. Some injection molding manufacturers can only produce according to your drawing but offer no advice, which may cause problems after you’ve invested in hard tooling. For example, an ABS clap may break due to a lack of enough impact resistance. WeProFab can advise you to choose POM and make an injection mold, which is fit for POM injection molding.

If you need an optical level helmet visor or LED lens, WeProFab could advise you on the structure design and do optical correction for you.

Secondly, choose an injection molding company that has a compatible mold process type to make your products. WeProFab holds different levels of injection molding machines, which can offer you comprehensive custom plastic molding services. We have small and large injection molding, over-molding injection molding, insert injection molding, medical injection molding, clean room injection molding, optical injection molding, low-cost injection molding, rapid injection molding, precision injection molding, etc.

Thirdly, you need to choose a capable injection molding supplier with a good quality control system. WeProFab has a strict quality control process from IQC, IPQC, OQC, and after-sales services. We adhere to the industry standard of ISO 9001: 2015, making sure all products we ship to you can meet your quality requirements.

Finally, the cost is a critical point that will help you have a competitive advantage over your competitors and gain more profits. WeProFab has been working on the TCO (Total Cost of Ownership) program for a few years now. We are professional on how to save costs for our customers from tooling design, raw material selection, production efficiency, storage, logistics, after-sales service, etc.

For more information about WeProFab, just send inquiries to us.

Plastic Injection Molding – The Ultimate FAQ Guide

What is Plastic Injection Molding?

It refers to a manufacturing process of producing plastic parts in large volumes by injecting plastic molten material into a mold.

It is a basic conventional manufacturing process that involves creating a relatively hard tool out of plastic then using it to mold large quantity plastic parts.

What is Co-injection Molding Plastic?

It is a manufacturing process which involves the injection of two dissimilar processes for producing a plastic part which has a skin and core laminated structure.

Co-molding

You can as well refer to injection co-molding as a sequential type of multi-component technology which involves the injection of a core component into the skin, which happens to be the first component.

Do Injection Mold Classification Matter?

Yes in three great ways.

The first is that it helps in cost reduction since you’ll be using fairly affordable material for the core components.

It also matters because it allows you to increase part properties.

In this case, it means that you’ll have parts with higher mechanical strength despite the high surface quality.

While at it, you will also be able to get improved part quality.

Lastly, the classification of injection mold is also essential since it allows you to enhance rapid delivery.

This is in the sense of delivering low volumes of parts possibly within one or two weeks.

When Should You Modify Mold in Plastic Injection Molding?

When you need to produce low scrap rates.

This process does not cut away substantial percentages of an original plastic block.

Plastic injection molding

When you need to enhance brand consistency by reproducing identical parts.

You need to know that injection molding is repeatable hence can enable you to practically reproduce identical parts to the first one.

What is the Difference Between Insert Molding and Over Molding?

Over molding refers to the process of adding another layer of material over a polymer part.

For example, it happens when you overlay a material onto a plastic substrate to form an introducer.

Insert molding, on the other hand, refers to a combination of plastic material and/or metals into a single unit.

In most instances, applications that require insert molding often use it to add metal pins and bushings to an already molded plastic part.

Are there Plastic Fabrication Technique to Substitute Injection Molding?

Yes, quite a several including the following;

Low-pressure molding– it incorporates gas-assist molding and structural foam molding.

Gas-assist molding is reasonably effective since it fills the mold using material popularly known as short-shot.

Structural foam molding comes in a core encased in a solid form with molded parts that have a higher strength to weight rations than those made by injection molding.

Co-injection – is also the other fabrication technique for plastics.

It is also known as sandwich molding and uses a designed nozzle to inject two materials into a mold to allow one to completely encapsulate the other.

Other commonly used plastic fabrication methods in place of injection molding include; reaction-injection molding, rotational molding, and shaped thermoforming among others.

What is the Difference between Co-injection Moulding and Bi-injection Molding Plastic?

The major difference between these two types of molding techniques is that co-injection involves the injection of two different materials using similar injection locations.

Bi-injection, on the other hand, involves the injection of two different plastic materials at separate injection locations with independent process controls.

What are Plastic Injection Molding Advantages?

Some of the main advantages of plastic injection molding include:

• Provides you with unmatched versatility for producing different types of parts and products for a wide range of applications
• Allows you to use multiple plastic types simultaneously which you can carry out with help of co-injection molding.
• It is an automated process hence most of its functions are performed by machines and robotics that a sole operator can control and manage.
• This helps in saving manufacturing costs.
• Provides a high level of efficiency throughout the manufacturing process.
• The high production output rate makes it possible for the cost-effective and efficient too.
• It provides detailed features as well as complex geometry which helps in producing complex and intricate shapes for different products.
• Produces relatively stronger products since you can use filters to reduce plastic’s density and adding strength to the molded part.

Which Variables Affect the Cost of Plastic Injection Molding?

Parts of injection molding machine

Part size – the larger the part the more the material you’ll use which translates to relatively more spending.

Part design – a complex part translates to an intricate mold which implies that you’ll require higher tool costs.

Part tolerance – if you’re producing parts with somewhat tight tolerances, you’ll need additional steps when manufacturing mold leading to an increase in tool cost.

Resin choice – the value, quantity, and availability of the particular resin you choose for plastic injection molding affect the cost directly.

Tool material – the material you choose for a particular plastic mold will have an impact on its cost.

Cycle time – precision build in attaining uniform cooling of and fast machine cycle leads to increasing in tool construction and maintenance costs.

Volume and cavities – high volume projects are contingent on higher quality tools which reliable service hence making the tools comparatively costly.

Which Size Part Runs are Economical in Plastic Injection Molding?

Short size part runs are comparatively economical in this process since it bridges the time gap between full production and prototype.

It is also regarded as economical since it is reasonably faster and focuses on simple parts which are apparently easy to produce.

Can Thermosetting Plastic be used in Injection Molding?

No.

The reason is that thermosetting plastic can never be melted and reformed.

Such plastics are also comparatively less impact-resistant in harder forms hence tend to easily shatter and improvise the quality of the part.

How Much Does Plastic Injection Molding Cost?

The general cost of plastic injection molding is dependent on several elements including a combination of part size, material, complexity, and expected quantities.

Is Plastic Injection Molding Blister Packs Profitable?

Yes. It is profitable in two major ways;

It is because it is less complicated to make these packs compared to other plastic packaging techniques.

What’s more, is that numerous packs can be produced at once to contain various items hence deferring the cost of having multiple packs.

Injection-molded blister packs

How Do You Determine Realistic Plastic Injection Molding Tolerance?

By having an appropriate understanding of established standards that you need to follow including ISO, ASTM, SNAP, GRACol, and A2LA among others.

Finding out what your competitors are also doing and the way they also work is another suitable way of determining tolerance in plastic injection.

And upon determining that particular application for the material, you can also choose to engage your customers regarding the particular tolerance they’d prefer.

Can you Achieve Tight Tolerances in Plastic Injection Molding?

Yes. But you need to have specialized tools and equipment, which in many instances are quite expensive to obtain and operate.

When is Plastic Injection Molding Uneconomical?

Several instances including;

• Achieving tighter tolerances
• Producing a low quantity of part materials involves an extensive process.

How do You Fix Burn Marks in Injection Molding Plastics?

There are two major ways of approaching this;

a) Trying to reduce the clamping force.

Remember that when a clamping force is set too high, it tends to compress the molds, and vents are pinched closed.

b) By using your fill rate regulator to slow down the fill rate during the last 10% of the mold filling.

But when dealing with a machine without fill rate control, you can always choose to set the first stage injection time to stop before the mold is full.

Afterward, you can proceed to a lower second stage for the final fill.

Whichever way you choose, both of them will always give air more time to escape.

What is Injection Molding Plastics Design Considerations?

They include the following;

• Radius
• Wall thickness
• Draft angle
• Part lines
• bosses
• Ribs
• Apt gate location

Does Plastic Injection Molding Produce Toxic Fumes?

Yes. Some of the common toxic fumes produced during plastic injection include hydrogen chloride, acrolein, butadiene, formaldehyde, and phenol among others.

However, the exact composition of the fumes tends to vary depending on numerous aspects.

The immediate effects nonetheless include irritation to the nose, eyes as well as lungs.

What are Injection Molding Best Practices for Optimal Plastic Fabrication?

They include the following;

Wall Thickness of Plastic

• Maintain consistent wall thickness throughout
• Eliminate unneeded thickness and wall stock
• Use the ribs to reinforce the wall without necessarily adding to the thickness
• A 10% increase in thickness is equal to a 33% increase in stiffness.

Undercuts in Plastic

• Always ensure that you minimize them as much as possible since they add cost to the mold.

Tight Tolerances in Plastic Injection Molding

• Always make sure that you utilize low shrinkage materials for parts that have relatively tight tolerances.

Corners and Transitions in Injection Molding Plastic

• Ensure that you use gradual transitions if at all you have to change the wall thickness.

Ribs and Bosses in Plastic Injection Molding

• Make sure that you design the ribs and bosses to approximately 60% of the joining wall thickness to reduce the risk for sink marks.

Draft

• Maintain a minimum of 0.5° draft angle on all the features which are perpendicular to the parting line.
• Nonetheless, the ideal angle should always be 1° to 2°

What Plastics Are Used in Injection Molding?

The most common plastics you can use in injection molding include;

• Polyethylene
• Polycarbonate
• Acrylonitrile Butadiene Styrene
• Polyamide
• Polypropylene
• High Impact Polystyrene

How do you Process Plastic for Injection Molding?

You need to check the mold surface specifically the cavity and core for rush, flaws, and bare among others.

Then check carefully the capacity at the hopper, the color, warming up the system, and all other related components to ensure that they are working accordingly.

While at it, ensure that you remove moisture appropriately from the plastic material.

Also, you need to calculate the material weight following the overall quantity of the product.

Still, prepare the cooling channel, jig, and insert.

Is Plastic Injection Molding Good for Short or Long production runs?

It is ideal for short production runs because it presents comparatively more benefits than long production runs.

The short production run is also becoming a niche segment market that is serving a highly specialized market.

Its ability to release-ready injection molded parts to the market after a few days makes it more a relatively better option.

Are there Limitations of Plastic Injection Molding Parts?

Yes! They are quite a number but the main limitations include;

• Limit in the design which you can create through injection molding
• The mold requested by clients must fit the parameters set within injection equipment’s limit.
• The thickness of the end product is dependent on materials and design to use.
• The initial tooling cost for the entire process is also quite expensive in addition to investing in the equipment.
• It presents a number of part design restrictions making the entire process quite involving and somewhat tedious.

How does Plastic Injection Molding Work?

It essentially involves the production of molded products by melting molten plastic materials by using an injection molding machine into a mold.

What happens is that you melt the plastic beads then force them in a vacuum between two specially-formed plates (Cavity and core) often made of steel.

Machine manufacturers will always ensure that they make the plates in accordance with the design supplied by the engineer.

The cavity takes a shape of a deep hole whereas the core plate has a drafted cylindrical protrusion both mounted on steel bases with matching holes and pins for precise alignment.

So it happens that you mount the two halves within the molding machine centered around the point where the production of hot plastic occurs.

The molder then adjusts the various parameters of the machine including temperature, and cooling time among others accordingly, and sets it into motion.

Once the machine is set, the molder can leave it to continue operating unattended though there are instances when he/she needs to monitor the progress.

The machine heats the raw plastic resin pellets, injects them into an empty cavity of the mold under great pressure then opens to eject the finished part.

In every 30 seconds or so, the machine shall be opening, ejects a fresh, new plastic part, closes, and the cycle repeats.

So in general, this process involves the following steps, mold preparation, set up, mold closing, injection, cooling, mold opening, and removal of product.

Plastic injection molding equipment

When Should You avoid Prototype Plastic Injection Molding?

When you require relatively large part quantities particularly for low-volume production.

How Do You Choose Plastic Injection Molding Machine?

• Ensure that you choose the right model series from the numerous that are available on the market.
• The machine should be able to put it on in connection with mold size, thickness, and dimension among others.
• It should have enough injection quantity and fast injection speed.
• Ensure that you also check the performance parameters of the machine in the product manual.

What are the Common Plastic Injection Molding Defects?

• Warping
• Vacuum voids
• Flow lines
• Burn marks
• Weld lines
• Sink marks
• Discoloration
• Jetting
• Flash
• Short shot
• delamination

What Types of Injection Molding Plastic are There?

There are two major types of injection molding in plastics which include; cold runners and hot runners.

Can you Suggest Plastic Injection Molding Tests?

• Physical and mechanical testing
• Chemical testing of polymers
• Barrier and permeation properties testing
• Accelerated weathering testing
• Optical and electrical properties testing
• Thermal, auditing, and system certification testing

Which Industries Use Plastic Injection Molding?

• Aerospace
• Automotive
• Medical and pharmaceutical
• Commercial construction
• Packaging
• Food and beverages
• Consumer products

Which Types of Products are Suitable for Plastic Injection Molding?

• Automotive parts and components
• Musical instruments
• Storage containers
• Toys
• Electronic housing
• Household materials
• Point of purchase products such as spring-loaded supermarket display tray
• Sporting goods like exercise tools and training devices
• Deck fasteners, roofing vents, and railing gaskets

Building Plastic Injection Mold Takes How Long?

It tends to vary depending on a wide range of factors.

However, the average duration ranges between 8-10 weeks, which is still dependent on the complexity and cavitation of the mold.

Why is Prototype Important in Plastic Injection Molding?

• Gives a better comprehension of the design intent.
• Alerts you on the possibility of early changes hence helping greatly in saving time and cost
• Helps in detecting design flaws as well as other issues that might occur at the design phase
• Enhances facilitation of cost-effective and efficient evaluation of part’s form, fit as well as function.

WeeTect Offers which Plastic Injection Molding Solution?

One of the plastic injection molding solutions you can get from WeeTect is Polycarbonate injection molding.

At select, we make many products through this technology such as helmet visors, face shields, and industry goggles among others are produced using this process.

Goggles             

Over-molding is the other common plastic injection molding solution offered by WeeTect.

Also, we can produce customized products, over-molding offers the best solutions since it enables in creating of colorful, comfortable, and ergonomic components.

And then WeeTect also offers insert molding particularly for creating threaded as well as electrical parts.

Does WeeTect have In-house Tooling System Design?

Yes.

It is located in WeeTect’s wholly-owned facility which is essential in making tooling designs relatively injection friendly.

WeeTact has a complete R&D center and testing facility in the Foshan factory.

All our injection molded parts are CE, and ANSI certified.

Can WeeTect help in the Secondary Assembly Process of Injection Molded Plastic Parts?

Yes. As long as all the particular injection molding design considerations are met in regards to the specific plastic part.

How does WeeTect Empower OEM Plastic Injection Molding Business?

By ensuring that we purchase and use the specific equipment and tools that meet the required standard specification and quality for the production of plastic injection molding.

WeeTect offers unlimited solutions in various plastic fabrication techniques.

These include plastic injection molding, bonding, cutting, drilling, etc.

We also offer excellent secondary operations such as stamping, printing, and flame polishing amongst others.

More importantly, WeeTect offers cost-competitive prices, with custom injection molded parts readily available.

Talk to us today to learn more about our support for OEM businesses.

How does WeeTect Control Plastic Injection Molding Quality?

a) Thorough Inspection Before and During the Molding Process.

At first, what happens is inspections to authenticate all the necessary part features before full production.

Immediately full production begins, inspections of tooling are completed by mold operators and craftsmen.

In addition, resin formulations are tested and also verified in our material lab using industry-standard testing practices and equipment.

b) Post Molding Inspections

At this stage, all parts are visually inspected once the unloading of the mold occurs.

Immediately it is verified, they are passed onto our finishing assembly area for what we refer to as possible post-molding and inspection activities.

These activities include; physical and mechanical property testing and part sampling from the pre-defined sample size.

c) Final Inspections

All the finished parts must undergo a final inspection by our quality system manager.

All the parts are visually inspected appropriately packaged to guarantee safe shipment and arrival.

WeeTect injection molded parts, depending on design and specifications, must pass the following tests:

• Refractive power test
• Impact resistance test
• UV aging test
• Hardness test
• Abrasion test
• Anti-fog test
• Viscosity test
• Spectral transmittance test
• Scattering test

WeeTect provides all the necessary certificates and works with third-party testing laboratories as well.

Which Types of CAD Files Do WeeTect Accept for Injection Molding?

WeeTect accepts a range of 2D and 3D file formats.

We have experienced engineers and technicians who can interpret and convert all your file formats.

We also help in the plastic components designs and concept development.

Does WeeTect Provide Free Samples for Plastic Injection Molding?

Once we evaluate your order, WeeTect will definitely send a free sample for plastic injection molding.