The Complete Low Volume Injection Molding Guide - Prototool

The fast-manufacturing sector is now through a period of substantial change. Due to this industry&#;s fast pace, things must be sent as quickly as possible. Product designers, engineers, and manufacturers are entrusted with ensuring that the quality of their products is consistent. Low volume injection molding is a part of manufacturing oriented toward addressing consumers&#; needs.

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With the use of this production method, manufacturers may make comparable, low-volume plastic components with consistent characteristics and qualities. Manufacturers are presently implementing novel operation techniques to get a competitive advantage in the marketplaces, which are continually changing. This thorough book will teach you all there is to know about low-volume injection molding.

What is Low Volume Injection Molding?

Low-volume injection molding is the optimal manufacturing technique for producing fewer than 100,000 units of a given component. Before committing to a long-term molding setup, it is used to mass-produce identical components; however, certain low-volume plastic parts may never need larger-scale manufacturing; therefore, it is utilized before making such a commitment. This molding is one of the most prevalent techniques used in the current manufacture of plastics.

MPM equipment is best suited for usage with plastic-molded objects with modest production quantities. They are cost-effective, need a small footprint, and can use low-cost tools with a single cavity. Low-Volume injection moulding machines are ideal for prototype, bridge manufacturing, and ASTM specimens, among other uses. These devices can also accommodate requests for lesser quantities.

Low Volume Injection Molding VS Traditional Injection Molding

The production rate is one of the most distinguishing features of low-volume injection molding compared to traditional injection molding. Traditional injection molding requires much more time than low-volume injection molding.

Additionally, the mold designs for conventional injection molding are more complex, which may increase the time necessary to create the components. Due to this, preferring low-volume injection molding over more typical methods has many advantages.

injection molding parts

Advantages Of Low Volume Injection Molding

One of the most necessary processes in the world of rapid manufacturing is Low-Volume plastic injection molding. The model&#;s continuous development may reduce production and shipping times. Unfortunately, the standard approach does not get results as quickly as you&#;d want.

 However, there are several ways in which the production process features go against the plastics market&#;s requirements. The time needed to manufacture the parts may grow much more if the mold design is complicated. Conversely, low-volume injection moulding is a practical method for swiftly resolving such concerns. To name only a few of its numerous advantages:

· Uses Softer Aluminium Tooling

In contrast to the more traditional method of molding, low-volume injection molding does not need the use of hardened steel mold tooling. As an alternative, it utilizes aluminum, which can be shaped more easily in molding. Aluminum&#;s hardness is much lower than that of steel. It makes using it a lot less complicated and quick, and easy.

The heat treatment process may be streamlined by skipping the annealing step when aluminum is used for tooling. Steel tools often need annealing to remove internal tensions and properly harden the metal. Furthermore, most surface treatments used for steel molds are also suitable for aluminum molds.

· Quality Parts Manufacturing

Although the tooling material used in low-volume injection molding is softer, the resulting products are long-lasting and functional. This production technique may be used to assemble many different products. Furthermore, aluminum transfers heat to steel at a far faster pace than steel does. The enhanced conductivity makes the precise positioning of the cooling lines moot. That way, it may add more mold parts. Consequently, low-volume injection molding bridges the gap between prototyping and mass production by providing more design flexibility.

Low Volume Injection Molding Cost

Many people falsely believe that they may save money simply by buying stuff. Although this is often the case, there are situations where it is not. While this may be the case with household goods, it is less certain with things utilized in the office. The materials used in production significantly impact the price tag attached to each final product. High-volume injection molding shops may sometimes have to meet minimum order standards. They may need to do this to cover their costs and make up for the high costs incurred during production.

Yet, low volume injection molding often has a far lower overhead than high-volume injection molding. In this case, manufacturers may crank out goods for sale without demanding minimum orders from buyers. That might be useful if you&#;re looking at plastic batch manufacturing on a small quantity of injection molding. Moreover, you won&#;t risk buying from a supplier that hasn&#;t updated its stock in a while. Because of all of these reasons, costs may be drastically cut down.

· Shorter Lead Times

The manufacturing approach not only helps keep the price of producing plastic components down but also helps boost the output of those components. It uses a technology that expedites price quotes for customer orders. The program also examines the component&#;s design to ensure reliable and rapid manufacturing.

Because aluminum is such a malleable metal, casting molds from it requires much less effort and time. You may increase the material&#;s longevity without resorting to hardening. Since the mold can now be sent to the factory, production can start in earnest. This is helpful for product teams of all sizes since it may shorten the time it takes to get a product to market.

· Flexibility In Design

Small-scale injection molding focuses on producing fewer units in a shorter time. Given this, a business&#; choice to make minor adjustments or changes to the design won&#;t have much of an impact. This method allows for iterative refinement of the product before it reaches the consumer.

High-quality plastic injection molding offers immediate feedback, which improves the product&#;s manufacturability. It allows fresh ideas to be tested in various industries before costly mass production is required.

· Bridge For Scale

A company that hopes to produce its items in large numbers in the future should start manufacturing plastic on a modest scale. It helps smooth the transition from prototype to full-scale production. Making a prototype that is suitable for mass production is now possible with the help of this technology. Beyond that, it helps improve both the product and the process.

injection molding in the medical industry

Disadvantages Of Low Volume Injection Molding

· Net Cost Of Tooling

While the cost of tooling will be less in isolation if they eventually switch to medium or high-volume molding, the overall cost will increase, Instead of jumping into a more permanent solution immediately.

· Shorter product Life

The savings may not always be worthwhile when factoring in the decrease in product lifespan. Our firm does not propose aluminum tooling until the product life is 20,000 components or fewer due to many design concerns that must be considered for this requirement.

· Design Constraints

More design constraints exist for low-volume tooling (often constructed of aluminum) than for high-volume tooling (due to metal&#;s inherent durability issues). A design that works well in a steel mold may prematurely wear out an aluminum mold owing to its features.

Low Volume Injection Molding Applications

Three of the most prevalent uses for low-volume injection molding are:

• Rapid prototyping
• Small Quantity injection molding
• On-demand or custom injection molding

Alternatives for Low Volume Injection Molding

· 3D Printing

This process is one of the most cutting-edge approaches to producing high-quality goods in small batches. Three-dimensional printing reduces production times and costs by eliminating the need for mold creation at the outset. Layered surfaces are common on 3D-printed objects. However, the surfaces may be sanded and painted easily to provide the required surface quality.

· CNC Machining

CNC machining is one of the oldest manufacturing methods, but it is still widely regarded as one of the most reliable ways of making things in low to medium quantities. It&#;s versatile, and you may apply it to various materials. It&#;s useful for making accurate molds, patterns, or dies that may be put to use in a wide range of manufacturing procedures.

· Thermoforming

Another effective technique involves creating molds to hold a thin plastic sheet in place while it is heated. Once the plastic has been heated, it may be shaped by adding pressure, a vacuum, or another mechanical force. The plastic sheet will conform to the shape of the mold, and any surplus will be cut away. Pressures and temperatures at the bottom of the scale are required for this method. There are a few inexpensive things you&#;ll need to build the mold.

· Urethane Casting

Another excellent alternative to prototype injection molding is urethane casting. Compared to the alternative process, urethane casting stands out since no up-front costs are incurred. In order to finish the procedure, a master pattern of the product must be fashioned using either high-resolution 3D printing or CNC machining.

Final Thoughts

Low-Volume plastic injection molding is often used throughout the prototype and functional testing stages of product development. Finally, small-batch manufacturers like Apple and Tesla may use low-volume plastic injection molding to make finished parts. There are a few major considerations that must be considered when developing components for low-volume injection molding. The overall complexity, the part&#;s draft, wall thickness, and surface polish are all of these things. Manufacturers may save money on tooling and time spent producing their goods by eliminating unnecessary surface finishes from their molds.

The vertical and horizontal injection molding machines rely on the same working injection molding principle. However, each process has unique strengths in different industrial applications. Here is a closer look at each process to make the right choice for your project. 

VERTICAL PLASTIC INJECTION MOLDING

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The mold opens and closes on a vertical axis in the vertical injection molding. This configuration positions the injection mechanism at the top of the mold, allowing gravity to play a role in filing the mold cavities. The result is a consistent flow of molten plastic during injection and a quicker filling time. Also, gravity-assisted filling lowers the pressure and clamping force required.

The vertical machine also has rotary blades and open clamps in its design. These features allow the machine to operate with multiple concurrent processes during one cycle. You, therefore, get increased productivity, higher efficiency, and less manual intervention in between cycles with a vertical mold. 

However, compared to horizontal molds, pieces don&#;t automatically fall out of the mold after being ejected. They require a robotic arm or human hand to remove them from the mold once cool. Yet, this step can contribute to an inconsistent cycle time, which could cause damage to parts after removal.

HORIZONTAL PLASTIC INJECTION MOLDING

The mold moves side to side when opening and closing in horizontal injection molding. Due to this horizontal axis, gravity doesn&#;t influence the flow of molten plastic. This requires the injection machine to exert adequate pressure to fill the mold cavities. 

However, the horizontal orientation of the mold lets the molded part fall off once the mold halves separate. The part, therefore, doesn't require manual extraction upon ejection. The horizontal molds are also designed with extra cavities to allow for the production of more plastic parts per cycle. This feature is excellent for projects that require a higher volume of parts. 

OVERMOLDING VS. INSERT INJECTION MOLDING

Most products in our modern world combine thermoplastics and metal components to make a single product. While several processes can achieve this effect, over-molding and insert injection molding have become popular, cost-effective options. Here&#;s how they differ.

OVERMOLDING

The overmolding process involves a combination of different thermoplastics to make a single product. Manufacturers use overmolding to create plastic parts with rubber handles as a feature. The process begins with injection, leaving the first layer to cure. Subsequently, a second layer gets added, forming a single solid product. Overmold layers can be more than two, depending on your end-product design.

Usually, a rigid plastic forms the base, while a thin, rubber-like thermoplastic elastomer forms the outer layer. Thus, overmolding is good at improving the function of a tool. For instance, the process can add a soft plastic handle on top of the hard metal screwdriver. This also eliminates the need for parts assembly adhesives to fuse different plastic components.  

INSERT INJECTION MOLDING

The insert molding process shares several steps with conventional injection molding. Both involve the melting and injecting of molten plastic resin into a mold. The main differentiating factor from overmolding is adding more inserts to the mold as an extra step. This insertion may involve a human hand during low-volume production or a robot arm when high-volume production is requested. You can use this process to make parts with strong insert attachment points, improving the component&#;s overall strength. 

However, the mold used in insert molding needs a protective design to prevent high pressures and temperatures from damaging inserts. Damaged inserts make the entire product non-functional. Therefore, throughout the entire process, the position of the insert shouldn&#;t change. Firm placement of the insert &#; while the injected plastic cools &#; prevents any degree of displacement. 

The process showcases its versatility, as it can produce simple products to highly intricate parts. Industries such as the health sector have become major beneficiaries of insert molding. Medical sutures, implants, prosthetics, surgical blades, and dental instruments are products made from insert molding. 

Other advantages of insert molding include:

•  

  Reduced assembly cost

•  Increased design flexibility

•  Reduced material waste

•  Improved design strength

  
  

CLEANROOM MOLDING

Cleanroom molding involves using a special room to reduce the risk of contamination while making plastic parts. This unique environment allows the plastic parts to remain as clean as possible during manufacturing. High-efficiency particulate air (HEPA) filters remove airborne particles from the air, reducing the likelihood of adverse effects occurring in the molding process. Depending on your injection molder, external agencies annually examine and calibrate Cleanrooms to maintain the grade.

The design of a cleanroom is to control the molding process environmental condition like humidity, pressure, and temperature. This consistent environmental condition allows the maintenance of a stable molding process. Industries such as the pharmaceutical, medical, biotech, and military industries can rely on cleanroom injection molding to make special parts. 

Cleanrooms exist in several classes, ranging from Class 1 as the most sterile to class 9 as the least sterile. A more sterile cleanroom is ideal for plastic parts with extremely low tolerances for foreign debris, such as microscopic lenses. You can perform most plastic injection molding processes in Class 8 or 7 cleanrooms. 

•  Class 8. On site, you&#;ll find portable tenting surrounding the molding equipment while the room gets maintained under positive airflow. This regulation helps the injection molder achieve an ISO -1 standard. 

•  Class 7. This Cleanroom has more stringent standards when compared to a Class 8 Cleanroom. Hard walls enclose and separate the injection molding area from the rest of the floor shop. Air in this room also gets constantly cleaned and replaced to keep particular matter low inside the room.

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  PLASTIC INJECTION MOLDING POST-PROCESSING OPERATIONS