Injection molding is by far the most versatile of all manufacturing processes used for plastic parts. Applications for injection molded parts are virtually endless, ranging from automotive, medical and packaging to construction, consumer products, and more.

In this article we will outline how to maximize productivity in injection molding through the application of practical strategies, advanced technologies and optimal processing techniques. Whether you’re a manufacturer or an engineer looking to optimize your process, keep reading to learn everything you need to know about achieving high part production output without sacrificing quality.

1. Importance of Improving Productivity in Injection Molding

Improving productivity in injection molding is not only about producing more parts, it’s producing them faster, better quality and lower cost. Because injection molding produces billions of parts per year in industries such as automotive, aerospace, packaging, medical devices and consumer electronics, any gain in efficiency has an overall impact on profitability and market competitiveness.

There are several reasons why increasing productivity in injection molding makes sense. Here are a few key reasons:

1.1 Cost Reduction & Higher Profit Margins

Components produced via injection molding can be quite complex and often include many features, such as ribs, bosses, holes or recesses. In addition, the component may need to have critical dimensions within tight tolerances that are difficult or too costly to achieve by machining with tooling (cutting) alone.

1.2 Meeting Growing Market Demands

The demand for plastic parts worldwide has been growing at an alarming rate. Sectors like automotive injection molding and medical injection molding require large volumes of high quality parts, and often also in short lead times, particularly so with the demanding automotive injection molding sector. In many instances, if manufacturers do not continuously improve productivity then it is likely that their competitor will win more business due to being able to deliver larger volumes in short time.

1.3 Faster Time-to-Market

In any industry that is competitive, time is of the essence. The company that manufactures and delivers products the fastest has an advantage over its competition. Productivity improvement in injection molding facilitates companies to reduce lead times, introduce new products fast and respond to customer’s changing needs.

1.4 Enhanced Product Quality and Consistency

Productivity is not just about speed – quality also matters. Optimized injection molding processes produce parts with fewer defects, better dimensional accuracy and more consistent quality. Reduced re-work and customer complaints mean less time and costs.

2. Key Factors That Affect Productivity

There are different factors which define a machine performance and the understanding of these factors help to identify the areas of improvement as well. Indirectly, process parameters also involve some control over machine performance like.

2.1 Machine Performance

The machine the part is made in is the heart of this process. Its speed, reliability and energy efficiency all have an impact on productivity and a machine that may be old or not looked after could cause higher cycle times, inconsistent part quality or frequent breakdowns. Upgrading to either hybrid or all electric machines helps with precision, downtime and energy reduction.

2.2 Mold Design & Quality

Mold design plays a very important role in overall output and cycle time. Bad mold design may cause several defects like warpage, flash, short or ejection defects. Cooling effect takes up most of cycle time so less it is more production rate or output can be achieved.

2.3 Cycle Time Efficiency

The cycle time for producing each part— including injection, packing, cooling and ejection— determines how many parts can be produced per hour. Cooling alone takes up to 70% of total cycle time. Improvements can be made by applying optimization-aided mold temperature control, utilizing additive manufactured conformal cooling and automating the removal of parts after injection molding.

2.4 Material Selection and Handling

The material choice has an impact on flow, cooling rate, shrinkage, and final part quality. Bad-quality raw materials increase scrap and reduce overall machine efficiency. Poor drying, storage, and conveying of resins may introduce process defects (e.g., bubbles, discoloration, or brittleness) in the molded parts. Consistent production can only be guaranteed by using good-quality resins and an adequate material handling system.

3. Increase Productivity in Injection Molding

Injection molding machines are the most important part of the injection molding process. The quality, dependability and performance of those machines will tell how many parts you can make per a certain period of time. If it’s slow, have frequent and long breakdowns or the shot weight & process control is not consistent, your productivity surely cripple. Therefore, to improve machine productivity seems to be mission impossible for injection molders.

3.1 Preventive Maintenance Program

Preventive maintenance keeps injection molding machines in production longer by preventing unexpected breakdowns. Scheduling hydraulic, screw, clamp unit and injection unit checks, among a laundry list of other services, prevents minor issues from growing into full-blown problems. Lubrication and hydraulic leak checks, process overheating checks and inspections for worn out parts are all best practices to keep machine calibrated and running for optimized performance.

3.2 Machine Calibration and Optimization

Calibration is key to consistent part quality. Injection speed, pressure and temperature control on the machine should be calibrated regularly. A well calibrated machine will produce zero-defect parts with every shot, leading to less scrap and rework.

3.3 Upgrading to Modern Injection Molding Machines

Older machines may not be as precise, have long cycle times and use excessive energy. All-electric injection molding machines and hybrid models can help you improve productivity dramatically. These machines provide:

• Faster injection and clamping speeds.
• Lower energy consumption
• Precisely controlling molding parameters
• Decreasing cycle times

3.4 Proper Material Handling and Feeding Systems

Good machines are developed with co-rotating twin-screws if properly fed. Bad feeding leads to blockages, contamination and unstable melt quality therefore automatic drying and feeding systems will make the material always ready for processing without delays or defects.

4. Process Optimization Techniques

Process optimization lies at the core of enhancing productivity in injection molding. Irrespective of how good your machines and molds are, inappropriately optimized process parameters lead to long cycle times, erratic quality either over a production run or from shot to shot, high scrap rates and frustration.

Here are some process optimization techniques in injection molding:

4.1 Cycle Time Reduction

Cycle time is the total time required to complete one molding cycle – injection, packing, cooling, and ejection; thus directly determines how many parts can be produced in one hour. Minimizing cycle time therefore leads to substantial increases in productivity.

• Injection & Packing Optimization: Reduce material stress while minimizing required cycle delays.
• Cooling time optimization: As cooling frequently represents as much as 70% of the cycle, the use of advanced cooling systems i.e. conformal cooling, baffles and bubblers will serve for reducing this stage.
• Ejection improvements: A properly designed ejector system serves in reducing sticking and improving part removal.

4.2 Scientific Molding Approach

Scientific molding (also referred to as decoupled molding) is followed where each phase of the molding cycle is based on data and material science rather than assumptions.

• Consistent fill, pack, and hold processes to avoid part defects have been made the past.
• Viscosity curves, PVT (Pressure Volume Temperature) analysis , Process Capability studies.
• Conduct DOE to find most stable process window.

4.3 Material Handling Improvements

• Improper drying systems: Hygroscopic materials like Nylon & PET must be dried by proper.
• Automated feeding systems: Conveying of materials should be done efficiently without any contamination.
• Regrind ratio optimization: Usage of recycled plastic needs to be optimized maintaining mechanical properties.

Conclusion

Injection molding is one of the most crucial and popularly used manufacturing processes, especially in today’s competitive world. However, it is the productivity that decides the success of a manufacturer. To ensure higher efficiency, there should be an increased emphasis on preventive maintenance, scientific molding practices, optimized mold design and material management. The additional ways to increase efficiency and output include reduced cycle time, decreased downtime and automation.

Increasing production with injection molding is not as simple as throwing more material into a machine. It involves thoughtful planning for lower costs and higher quality. Work with your injection molder early in the product development phase to make sure you are designing-in all of the features required for optimal manufacturability.