Low Volume Injection Molding: Cost-Effective Small-Scale Production

Not all manufacturers have the capacity to produce high-volume plastic parts. So, what should startups and manufacturers with minimal budgets and design requirements do? Low volume injection molding is the most cost-effective method for manufacturing low quantities.

The target for low-volume injection molding is in the hundreds or thousands of units in quantity to be produced. With this method, manufacturers get to explore designs even at reduced tooling costs due to their limited production scale. The ride into the world of low-volume injection molding is going to be fun, so don’t fall off. Let’s go.

1. Understanding Low Volume Injection Molding

The natural first step in employing low-volume injection molding is in understanding its workings and processes starting from its definition and what areas of manufacturing it covers.

1.1 Definition and Scope

When it comes to low-volume injection molding, the quantities set to be produced are usually smaller. This is the direct opposite of high-volume production. Low-volume injection molding perfectly suits custom-made products and prototypes. The flexibility and budget-friendliness make it a practical method of producing parts with less demand. It is why many industries often employ this method of plastic parts production. This process follows the usual manufacturing principle and steps of injection molding technique, the only difference this time is the quantity being manufactured. 

A custom-made, high-quality mold manufacturing is the first step, then, molten plastic is injected into the mold. When cooling and solidification time for the injected material elapses, it is then ejected to reveal the final product. The automotive, aviation, electronics, and consumer goods industries are the key players in employing the low-volume injection molding process. This is sometimes done for market testing of new designs usually with enhanced features. The feedback that comes from the testing is then analyzed and debated which helps manufacturers determine whether to proceed to full-scale and mass-produce such parts. and that’s typically based on the acceptance or rejection of such new designs and features.

1.2 Benefits of Low-Volume Injection Molding

Is there really anything to benefit from low volume injection molding? Sure, there are, and we’ve highlighted a few of its most important benefits below.   

• Reduced tooling cost: As far as low injection molding goes, it doesn’t require many expensive tools, especially when the budget is lean. Businesses like startups can afford the tooling cost of low injection mold, as they introduce a product into the market. Because of that, no need to incur heavy tooling costs, and quality is still offered. 
• Faster Turnaround production cycle: No time is wasted while production is ongoing. That is, as a result of low quantity, the production cycle is quick. Products can be available in a short period. This is particularly essential with products that have high competition in the market thereby allowing quick and sharp responses from brands. All thanks to a simple production setup. 
• Design flexibility: When producing on a small scale, there is room for experimenting with design options. Design alterations and modifications allow product designers the freedom to infuse and remove ideas. This is majorly why low-volume injection molding is considered awesome for prototyping and product development, with the minimal cost incurred. Completing the prototypes determines if production can proceed to full scale.

2. Considerations for Low-Volume Injection Molding

Without carefully considering important parameters and features of its processes, having a full grasp of low-volume injection molding performance may be difficult. Let’s examine these parameters. 

2.1 Material Selection

Almost if not all production processes are hinged to material selection, injection molding isn’t an exception. It is the topmost factor manufacturers and designers consider in any production process. This is where they discuss concerns such as material availability, cost, and compatibility. 

Although, peak performance, top quality, and cost-effectiveness of the material to be used in low injection molding are also top priorities. Nevertheless, manufacturers should also consider materials’ mechanical properties, chemical resistance, and environmental features. This aids the understanding of the materials’ deployment for specific projects. 

In injection molding, thermoplastics are usually the go-to materials for selection. However, different materials offer different values. Materials such as polypropylene, polycarbonate, and ABS are applicable in various industries due to their cheapness and performance expectations. 

What’s more? Materials like liquid silicone rubber (LSR) and PEEK offer incredible biocompatibility, heat, and chemical resistance in applications that require them to be durable and sturdy. One last thing is the compatibility of the material to be selected. The low-volume injection molding must ensure the melt flow rate and cooling attributes align with the intended design. It helps to manufacture top-quality parts with consistent dimensions and a superbly smooth finish.

2.2 Tooling Options

Tooling options are crucial to low-volume injection moldings in terms of production volume, lead time, cost-effectiveness, and durability. In light of this, applicable tooling options vary in the benefits and drawbacks they offer especially in the high-quality mold manufacturing industry. Aluminum mold for example is a common tool that manufacturers employ in production. Aluminum is widely known for its high thermal common tool manufacturer. In addition to that, it saves cycle times by cooling faster. Its only drawback is its inability to last long, it is, for this reason, it is usually considered for low-volume injection molding.

Another tooling option for low-volume injection molding is soft tooling, technically referred to as elastomeric tooling. This is a more flexible tool typically suitable for quick production methods or prototyping. The flexibility of this tooling option creates opportunities for developing parts with intricate dimensions. Also, it is a cost-effective tooling option with its molds made out of flexible materials like silicone. Despite these wonderful qualities of this tooling option, its limitation is the volume it can produce and the quality of the part produced. 

Rapid tooling is a 3D printing technology type of tooling. It is a sophisticated tooling option gradually announcing itself in the low-volume injection molding method. It’s perfect for complex geometries, saves cost, and reduces the lead time that simultaneously increases productivity. Major limitations to this tooling option are compatibility of materials, intended production volume, and complexity of the part produced.

2.3 Design Considerations

As important as the above-mentioned considerations are, to low volume injection, they are by no means more important than design consideration. And the overall objective of these considerations is to get high-quality parts, at minimal cost. In design considerations, a few noteworthy factors are identified. 

First is the inclusion of draft angles. Draft angle facilitates the seamless ejection of molded parts from the mold. Consequently reducing turnaround time, and eliminating any chance of damaging the mold. With draft angles, the durability of the tool is preserved. 

In the same vein, wall thickness is also an essential design consideration. The evenness in wall thickness ensures sustained cooling that in turn removes any shrinkage problems, contortions, and sink marks. A sudden change in wall thickness is liable to distort the structural reliability of the part. For this reason, a steady wall thickness is advised. 

Similarly, part complexity is very crucial to saving the cost of production. It is clear that low-volume injection allows for design flexibility, but this is no reason to overcomplicate the design with extravagant complexities. The production cost and lead times are likely to increase on account of such complications.

 

3. Process Optimization for Low Volume Injection Molding

Your considerations are only as good as the level of optimization of the molding process. Process optimization in low-volume injection molding itemizes the operations required to complete a low-volume injection mold. Frankly, these are essential steps that can make or mar the molding process not minding that it’s a small-scale production run. 

3.1 Process Parameters and Settings

Here are vital parameters and settings you should note in any low-volume injection molding operation. 

• Speed: The speed of transfer of molten plastic from the barrel where it is melted to the mold is crucial for part formation, efficiency, and performance. Injection speed can be responsible for short shots or excessive pressure if the speed applied is too fast or too slow. Also, cycle time can be bumped up because of this.
• Temperature control: The temperature is bound to affect part production in two ways. First is the required melting temperature, this regulates the melt flow rate of the material into the mold. The second is the mold temperature, this ensures cooling is maintained and effective. The proper control of both imparts a positive outcome and vice versa.
• Injection pressure: Like the injection speed, the injection pressure is important to avoid vacuums and sink marks in the part. Efficiently controlling the injection pressure maximizes the part’s structural reliability and precise geometry.
• Cooling cycle: The cooling cycle which is enhanced by the mold temperature is necessary for quicker part solidification. But the opposite leads to distortions and stress.

3.2 Quality Control and Inspection

Maintaining industry standards and requirements is hugely impacted by the level of quality control and inspection practiced on your production floor. Low-volume injection molding like every other molding technique is not exempted from regulations that mark standards and quality. The purpose to which this is done is to identify possible lags in part production. Various ways of implementing quality control include visual inspection, measurement of intricate geometries, and alignment of finishes. Visual inspection properly conducted reveals surface defects, while geometrical measurements should align with the stipulated dimensions of the industry. 

Furthermore, in-process quality control measures can be adopted to quickly identify possible errors that can be eliminated before production is completed. And if not, post-production processes are usually in place to correct necessary defects. In-process quality control measures include monitoring temperature, injection speed, and injection pressure. Consequently, regular maintenance of equipment, documentation, traceability, and in-line procedures that contribute to effective quality control are all quality management standards that translate to excellent part production and professionalism. Adherence to both process optimization parameters for low-volume injection molding ensures manufacturers get the best out of the process.

4. Applications of Low Volume Injection Molding

A huge part of any manufacturing technique, low-volume injection molding inclusive, is their specific applications. Here, we have some of the most unique applications and industries that feature low-volume injection molding. 

4.1 Prototyping and Product Development

Prototyping and product development remain major ways of applying low-volume injection molding. Product designers occasionally come up with ideas that they envision success in the real market. What better way to bring ideas to life if not by adopting the low volume injection molding. This is why designers and manufacturers opt for prototyping with low-volume injection molding, especially when they understand the benefits that accompany low-volume injection molding. The budget for product development may be lean, and a market review of new innovative products may be necessary to decide to go full-scale. 

Moreso, low-volume injection molding saves time and resources once the review comes back positive and committed to mass production is implemented. It might just need a little design adjustment before manufacturing in high quantities. Such adjustments tend to eventually become the driving force for sales and increased rate of turnover for that product. But first, a limited quantity is manufactured to gather feedback on possible ways to improve the product. Low-volume injection molding when compared to other traditional methods diminishes the risks and cost in terms of quantity manufactured. 

4.2 Custom Parts and Small-Batch Production

Low-volume injection molding excels brilliantly in manufacturing custom parts. It is a more cost-effective option than conventional ways of manufacturing low quantities like high-quality CNC machining. Other methods of producing plastic parts in low quantities tend to cost more as they are typically inclined to manufacture in high volumes. Furthermore, the time taken to manufacture custom parts employing conventional methods is longer compared to the cycle time of manufacturing with the low-volume injection method. Its capacity to manufacture custom parts is unmatched. Some parts are required for specific purposes, hence the reason for customization. This customization can offer precise geometries, incredible performance, and reduced cost of production when employing low-volume injection molding. 

Similarly, low-volume injection molding is highly recommended for small-batch productions. Now, small batch productions are likely to happen when the product is a limited edition, there’s an irregular demand for the product, or the product is tested for market review for possible adjustments before proceeding to mass production. Utilizing low-volume injection molding eliminates high overhead costs of production and simultaneously reduces waste. In case there is no need to continue the production of such parts, no further resources would be deployed. 

4.3 Spare Parts and Replacement Components

All equipment produced requires a spare part or a replacement component. Many if not all industries depend on the replacement or repair of their several products as an incentive to their customers. That being the case, they typically rely on an immediate replacement made available for such events. However, conventional ways of producing such parts require a demand for high quantities. Asides from that, the lead time for such productions is way longer than usual, accordingly the employment of low-volume injection molding for creating replacement components and spare parts. With low-volume injection molding, mass production won’t be necessary and cost is saved. In addition, lean time is reduced. In the electronic industry, components with legacy products that are no longer in production find cost-effective ways of manufacturing parts for existing products. This means the products still in existence are limited. For such products and companies, low-volume injection molding would be their best bet for manufacturing parts for their existing loyal customer. This way the company’s product is extended and isn’t allowed to become extinct. If there exists a fast and cheaper method of manufacturing spare parts and replacement components, low-volume injection molding is here to serve this purpose.

Conclusion

To wrap up, low-volume injection molding is a reliable way of creating excellent parts that function optimally, at an affordable cost. On that account, manufacturers and product developers, and designers turn to this cost-effective means of part production. With benefits such as reduced tooling cost, faster turnaround production cycle, and design flexibility, it’s no mystery as to why it is sought after by manufacturers. However, certain considerations determine its success. This includes material selection, tooling options, and design considerations. Its applications are not limited but include prototyping and product development, custom parts and small-batch production, and the production of spare parts and replacement components. If all these are your project requirements, then you’ve found a tested and trusted method of small-scale production.