It’s a pretty safe assumption that you’d like to save money on your next injection molding project. It’s also probably safe to assume that you’ve been actively trying to do so. Yet with a process as versatile as injection molding — one that can meet countless needs and be used in so many ways — there are also many ways to achieve further cost savings, which differ from job to job and application to application.
What’s more, the definition of “cost savings” can vary depending on where you’re looking to reduce costs. Shorter-term cost savings might include cost per part or finishing services on a specific job. Longer-term cost savings can come in areas such as decisions about mold manufacturing, or big-picture adjustments to the design principles that your engineers follow.
With all of that in mind, this piece is intended to provide a little bit of everything, which will hopefully help you get direct results in your next project, or to at least start thinking about your product and mold designs in a different way — to identify more opportunities for cost savings.
We’ll start with a big-picture topic (with which many readers may be at least partly familiar) and move forward from there.
1. Follow injection molding best practices: This is a key tenet of injection molding, and while it may seem obvious, it falls by the wayside all too often. Why? You may hear numerous reasons: a perceived interference with the form or function of the part, a lack of time, or even a lack of knowledge of these best practices. Though the simple fact remains: A part designed in adherence with best practices can be manufactured more quickly, more efficiently, with fewer errors — all adding up to lower costs. As an introduction (or refresher) to these best practices, here are some factors to consider:
- Incorporate draft into the design: Draft, or a slight angle to vertical walls, allows for easier part ejection.
- Round your corners: Ninety-degree corners are the enemy of good material flow. With rounded corners, material can much more easily flow through the entire mold cavity, resulting in higher part quality and fewer (costly) rejections.
- Create uniform wall thicknesses: Unless the design and function of a part absolutely requires it, uniform (or close to uniform) wall thickness helps in material flow and allows each part to harden more consistently. Varying wall thicknesses create uneven cooling in the material.
- Use core cavities: For parts with hollowed central areas (such as boxes or packaging), a core cavity is a much more efficient way of designing the mold. Essentially, the mold is manufactured around the “empty” part of the product (or the core), rather than machining the walls of the product into the mold, requiring a very deep, narrow cavity.
2. Consider volume in the process: Of course, the higher the volume of parts you’re producing, the lower your cost per part will be. However, that doesn’t help if you only need a run of 20,000 parts — let alone 1,000, or just one. Shorter runs can also be produced by different methods than those used for long runs — which can start driving down your cost per part in a big way. If you’re in need of a short or medium part run, still want to use a molding process, and don’t want to invest in a costly steel mold, using a different mold material can be a big help. Look at silicone molding or neoprene casting, for example.
3. Simplify your design: Fewer part features and geometries — and greater simplicity — will always make your part easier and, thus, less costly to manufacture. Take an objective, dispassionate look at the design of your product, and remove any unnecessary features, designs or other aspects that aren’t critical to the performance of the part. This can be a difficult process for someone who has worked hard on designing a part a certain way, but can definitely yield cost savings that make it worth it.
4. Eliminate unnecessary production and processes: Overproduction has thrown off many a P&L, often without anyone ever realizing it. In injection molding, that means to make sure you’re only using as high-grade a material as required for the part function; that the mold material is in line with your needs and expectations for performance and shelf life; and that you’ve eliminated as many finishing processes as possible (following design best practices and simplifying your design can help with this). Also consider the aesthetic needs of your part: While the appearance of most injection molding plastics isn’t necessarily attractive, it also doesn’t need to be for the majority of industrial needs. Eliminate any unnecessary dyes and pigment processes, as well.
5. Look at manufacturing partners for outsourcing: In-house injection molding is costly — there are no two ways about it. While it may be tempting to incorporate in-house injection molding — or expand on your existing capacity — to fulfill additional orders, it’s also a huge investment that can take a long time to recoup. Seeking a manufacturing partner for injection molding removes the burden of machine investment (and maintenance, operation, replacement, etc.) from you, and allows you to focus simply on providing a part design and relying on the partner’s expertise.
6. Research and choose the right partner: If you’ve decided to outsource your injection molding, choosing the right partner is another area where costs can be higher or lower, depending on the approach taken. Inexperienced facilities, or those that may have different specialties than what your project requires, can indirectly increase costs. The process may take longer, it may be more prone to misunderstanding or error between the two parties, and the quality may not be up to your expectations. Be sure to research your options extensively. Look for an experienced facility with its expertise on display — readily available for you. Shops that offer related services can also reduce your costs by incorporating prototyping, design, fulfillment and more into the production process.
With these tips in mind, you’re now ready to start identifying ways to lower costs for your injection molding projects — something you may not have previously thought possible. The lowered costs you can see across the board will make your time and energy investment well worth it.
