What Is Plastic Injection Molding? Every day, around the world, countless plastic parts are created by the plastic injection molding process. A machine clamps two sides of a metal mold together and then injects molten plastic. After a cooling period, the mold sections open and the machine ejects a brand-new part. While the process is simple to describe, injection molding companies need talent, tooling and technology to produce a top-notch part.
The molds that enable this process are precision machined, allowing for the production of on-schedule, high-quality parts for reasonable and efficient costs. Plastic injection molds fall into two general categories:
- Insert Molds – Molds used for insert molding are ideal for small and medium-sized parts, these single-cavity molds are a high-quality, economical solution for low-volume orders requiring a rapid turnaround time.
- Free-Standing Molds – The choice for high-volume production, free-standing molds include the mold base, inserts, and other components necessary for SPI standard injection molding machines. Though costing more and requiring lead times of up to 16 weeks, their ability to handle multiple cavities can reduce per-part cost.
While a plastic injection mold consists of only two sides, each section may have dozens of precision-machined parts. MSI’s in-house injection molding manufacturers can machine your mold to a tolerance of a thousandth of an inch, less than the average diameter of a human hair. Strength goes hand in hand with that precision. Molds may encounter clamping and injection forces ranging into thousands of tons.
Releasing an intricately designed part from a mold is a challenge for all injection molding suppliers. When mold elements must move to permit a release, many molders employ the “hand load” technique. With this method, selected mold components eject with the part.
Technicians then manually reinsert the mold pieces before the next cycle. MSI Mold prefers to implement automatic side actions, a method that keeps all mold elements in place. Choreographing the movement of multiple metal components is not easy, but the effort pays off with consistently higher quality and shorter cycle times.
What Services Do Top Injection Molding Companies Offer?
Plastic injection molding companies may specialize in a niche or offer a broad range of solutions. Typical services include:
Plastic Product Design
Parts to be manufactured are born in the design stage, and that process requires computer-assisted design expertise. If a customer does not have CAD software, plastic injection molding companies such as MSI Mold offer free CAD design services for all customers who purchase custom plastic molds. We can work with the simplest of sketches to create complex three-dimensional designs.
Prototype Injection Molding
After completing a 3D CAD model, building a prototype injection mold can ensure a trouble-free production run. While prototype injection molding was the only option for decades, many companies now employ 3D printing technology.
3D printing of prototypes offers low cost and single-day lead times, but the time-tested injection molding process still has compelling advantages. Unlike a 3D-printed model, using a prototype mold can reveal potential problems before production. Typical future production flaws exposed by molded prototypes that printed prototypes may not reveal include:
- Surface defects such as flow marks or knit lines
- Dimensional errors from material shrinkage
- Warping or possible voids
These issues are straightforward to address with the production mold or another prototype mold. Yes, there is a cost, but the value proposition is obvious: Proven molds lead to trouble-free production runs, and smooth production yields profits.
Custom Injection Molded Plastic Part Production
With a thoroughly tested mold in hand, you are ready for production. When selecting your production partner, look for custom injection molding companies with proven ability to produce parts with your chosen plastic and the production capacity for your order size. MSI Mold specializes in custom runs of 100 to 100,000 units per order, and we keep high-demand plastics in stock at all times.
Once produced, a plastic part may be packaged directly into a shipping box or require additional work. MSI Mold offers these in-house, post-molding services:
- Boring and reaming for close tolerance holes
- Machining for difficult to mold features
- Pad printing to add information or logos
- Plating of various types of metals
- Packaging with layer packing, cell packing or poly bagging
- Assembly of multi-part products
What Are the Cost Factors for Plastic Injection Molders?
When a plastic injection molder provides you with a quote for your part, a myriad of inputs come into play. The factors having to do with injection molding cost include:
- Workforce Quality – In any human endeavor, talent and experience costs money. MSI Mold team members have skills honed for decades, and retaining this talent is a high priority.
- Machinery– A high-caliber workforce needs the right tools to produce parts that customers deserve. Our multi-axis, computerized numerical controlled machines represent a substantial investment. Equipped with our CNC machines, our team has delivered for demanding customers worldwide.
- Material Choice– High-quality plastic can range from $1 to $25 per pound, and large-sized parts increase costs proportionately.
- Cycle Time – After material costs, the time from mold closing to part ejection is the single highest cost factor in custom production molding. Material choice is a factor in the molding cycle’s necessary cooling period and contributes to the overall cycle time.
- Part Complexity – Thick walls and undercuts add complexity to the molding process. Likewise, the thin ribs that add rigidity to your part often complicate mold building. If your part must meet rigorous specifications, you may have little flexibility on design options.
What Are the Benefits of Partnering With a U.S.-Based Injection Molder?
While offshore companies may offer low-price quotes, U.S. plastic injection molding companies bring compelling advantages to the table. Beyond the benefits of faster delivery and lower shipping costs, consider these factors:
- Shorter Lead Times – Delays in the make-or-break prototyping stage can eat into profits. With an offshore molding company, you must factor in additional days for international shipping and higher chances of unscheduled shipping mishaps. Multiply these over a few revision cycles, and much of the apparent cost savings evaporate.
- Tooling Maintenance and Support– With multiple high-volume runs, prompt maintenance of your molds can ensure that you deliver the quality parts your customers demand. Engineering changes are often required as customer needs evolve, and a U.S.-based molder is well-positioned to make these changes. As for support, MSI Mold guarantees your molds for the life of your production requirements.
What Qualities Define the Top Injection Molding Companies?
In-house capabilities separate great plastic injection molders from the pack. With designers, engineers, process technicians and sales staff able to work as a coherent unit, there are very few communication difficulties and customer needs receive laser focus.
Beyond in-house services, see how many plastic injection molding companies can tick off the items on this checklist:
- Experience – MSI Mold’s management team brings three decades of experience to plastic injection molding solutions.
- Commitment to 5s Lean Manufacturing Principles – MSI Mold’s quality, repeat customers, and affordable pricing demonstrate our ongoing commitment to lean manufacturing.
- Manufacturing Site Visits– Customers are welcome to visit MSI Mold and see our team in action.
- Respect for the Environment – MSI Mold’s injection molding machinery is entirely all-electric servo-driven. These machines halve the energy consumption of older hydraulic machinery and empower our molding professionals with a super clean
- Project Planning – When you partner with MSI Mold, our project engineer works with you to frame an advanced quality plan. Our experience enables us to head off time consuming headaches before they happen, and establish a roadmap to produce and ship your products consistently you need it.
MSI Mold injection molding services can provide you with the excellence you expect and the quality you deserve throughout the production life of your products.