There is a point in any new project where the decision must be made of how to create the components and overall product. It usually involves a decision matrix weighing the function of the product, the environment it will be used in, the cost to make and retail the item at, and even more options. Fabrication is usually an option because the methods have tradition, and tools are easy to use. Engineered resins have entered the chat, and they are starting to take the place of traditional metal materials. If you haven’t given plastic injection molding a consideration as an alternative to traditional fabrication, you may be missing an option on your decision matrix.
Is Plastic or Metal a Better Option?
It is always a lively discussion between the merits of plastic against metal. Choosing one material over another must be a decision made after considering the advantages of each compared to the other. These topics are typically discussed between plastic and metal:
- What is the function? The function of the components and/or complete assembly need to be considered before a decision is made on a material. Does it need to be rigid, or can it bend under load? Does it require abrasion resistance between components or assemblies? Plastic and metal can survive with abrasion, both can bend, or both can be brittle depending on the situation.
- What environment is it used in? Environmental factors can limit the use of many materials, including plastic and metal. A corrosive material may limit the type of metals that can be used unless a strategic coating is used to prevent corrosive breakdown. The air where the item will be used could be moist continuously, and it may contain acid rain or saltwater. Both can degrade metal.
- What is the cost? In order for a product to show profit, cost must be discussed from raw materials to the retail pricing. Simple metals may be a low-cost option, while adding specialized coatings to prevent degradation or abrasion may increase the price significantly. A specialized resin for plastic injection molding may be a higher investment initially but not require secondary operations and coatings for a similar outcome at less overall cost.
How Can Your Product Be Made?
There are many ways to make a product depending on the material being used. Metals can be fabricated with machining, casting, welding, and more. Plastic injection molding can be less complicated depending on the final shape and the steps to achieve the shape required. Injection molding is capable of many shapes that aren’t easily achieved by metal, but as with anything there are limitations. During the process of a design review, injection molding should complete a ‘moldability check’ to ensure the parts achieve a minimum target of 90%. This targeted level will allow adequate design flexibility to make changes and increase the moldability for a more balanced melt flow, heat exchange, as well as uniform cooling inside the injection mold as the cycle completes.
How Many Parts Do You Need?
Knowing how many parts you will need to create can be a moving target. You may have an initial order quantity, but with success that number may continue to grow. Fabrication may look like the best option for a low number of parts, but the truth is that plastic injection molding can also be used for a low number or parts or for prototypes. 3D Printing (also described as Additive Manufacturing) has become more common for prototypes in some cases, but using a simple injection mold may be a more cost-effective and faster option depending on the situation. There isn’t a right or wrong decision on which manufacturing option is best. It should be discussed with your manufacturing and design teams to decide if plastic injection molding, 3D printing, or fabrication makes the best business sense.
How Fast Do You Need Parts Made?
During the design and manufacturing phases of a project, you may need parts quickly. Injection molds can take weeks to complete depending on factors including their design intricacy and the material they are made from. Simple plastic injection molds without moving parts can be made from a softer material quickly. If your design requires moving details and parts, the injection mold should be made from a hard steel. It can dramatically increase the time it takes to complete the mold. It may take up to 16 weeks to complete a complicated design ready to mold a million parts annually. If you need just a few parts quickly, 3D printing or simple fabrication may be the best option. As the number grows, the decision matrix should weigh the options between printing, fabrication, or an injection mold.
Are Recycling or Sustainability Options a Concern?
Recycling and being sustainable is a relatively new discussion topic for products. Most metals are recyclable, but secondary coatings can hamper their ability to be economically recycled. Fabrication and injection molding can produce equal amounts of scrap, and if you have a recycling initiative you may have to weigh your product material options carefully. Most injection molding materials can be ground into small pellets and reused in the future without secondary processing requirements. Very little scrap leaves the facility to be put in a landfill, and what does leave can also be utilized in other productive ways rather than directly polluting.
Your decision or design matrix should include discussion points on function, environment, quantity, and recycling to ensure the best manufacturing option is chosen for your product. Fabrication has tradition, but that doesn’t always equate to the best option. There are 1000s of resins available for plastic injection molding and they can offer a broad range of characteristics such as more flexibility, a harder surface, corrosion and temperature resistance, or more. A simple formulation can create the perfect engineered resin that can handle the harshest environments available. SEA-LECT Plastics has an elite team that produces world-class prototypes and products, and we have decades of experience with plastic injection molding. We can offer support to determine what type of mold you need, what resin to choose, and how to invest in your future. Give us a call at (425) 339-0288 or email us at mattp@sealectplastics.com. We’ll help to determine the best manufacturing for your next project.
Matthias Poischbeg was born and raised in Hamburg, Germany. Matt moved to Everett, Wash., after finishing his bachelor’s degree in business in 1995 to work for Sea-Dog Corporation, a manufacturer, and distributor of marine and rigging hardware established in 1923.
In 1999, Matt took over the reins at Sea-Lect Plastics Corporation, a sister company of Sea-Dog and a manufacturer of plastic injection molded products with an in-house tool & die shop. Matthias Poischbeg is also a contributor to Grit Daily.