11 practical ways to reduce costs without compromising design
Everyone wants to save money on manufactured parts. It sounds simple, but one of the easiest ways to reduce price‑per‑piece cost in injection moulding is by increasing part quantity. That is because the initial upfront cost to design and machine the mould amortises over more parts. At Konlida, for example, up to 25,000 parts or more can be moulded from the same tool.
However, maybe your moulding project calls for only a handful of parts. No worries. Konlida builds cost‑effective moulds for production quantities as low as 25 pieces, often within a few days of ordering.
How much does injection moulding cost?
While injection moulding may seem costly compared to processes like CNC machining and 3D printing, the ability to scale and manufacture thousands of parts makes it a cost‑effective solution for mass production.
The main determinant of moulding cost is the amount of time it takes to produce the tooling. The more complex the part’s geometry, the higher your manufacturing costs will be. Simple parts, without undercuts or advanced surface finishes, will be the most affordable.
In addition to per‑unit costs, consider the material. Many plastics overlap in strength and functionality, but some are inherently easier to mould, driving down part costs. You can experiment with different materials in the interactive quote you receive when you upload your design.
11 ways to stretch your manufacturing budget
1. Eliminate undercuts
Undercut features complicate and, in some cases, prevent part ejection. Get rid of them if you can. If that is not possible – for example, if you need a side action, sliding shut‑off, or pick‑out – consider alternatives like sliding shut‑offs and pass‑through cores, or changing the parting line and draft angles to provide an easier mould build. These reduce tooling costs as you avoid additional pieces to the mould that add to manufacturing costs.
2. Get rid of unnecessary features
Textured surfaces, moulded part numbers, and company logos look cool, but be prepared to pay a bit extra for these and other non‑mission‑critical features. That said, permanent part numbers are a requirement for many aerospace and military applications.
Use a mill‑friendly font such as Century Gothic Bold, Arial, or Verdana (sans‑serif fonts), keep it above 20 pt, and don't go much deeper than 0.25 to 0.38 mm. Also, be prepared to increase draft if part ejection is a concern.
3. Use a core cavity approach
If you need an electronics housing or similar box‑shaped part, you can either sink the wall cavities deep into the mould base, requiring long thin tools to machine ribs into the mould, or machine the aluminium down around the core and mould the part around it. The latter approach is known as a core cavity, and is a far more cost‑effective method of moulding tall walls and ribbed surfaces. Better yet, this makes it easier to provide smooth surface finishes, adequate venting, improved ejection, and can eliminate the need for super‑steep draft angles.
🔗 Related: Draft Angle Guidelines
4. Reduce cosmetic finishes
Pretty parts are nice, but they often require bead blasting, EDM, or high mould polish to achieve an elevated level of cosmetic appearance. This drives up tooling costs. Anything greater than a PM‑F0 (as‑machined) finish requires some level of hand work, up to an SPI‑A2 mirror finish using Grade #2 diamond buff. Avoid fine finishes such as these unless they are required for the job.
One thing to consider: let us know if you need the entire half of the mould polished or just one small area. You could save costs by only polishing the area needed versus the entire side of a mould.
🔗 Related: Surface Finish Options
5. Design self‑mating parts
Maybe you are designing a snap‑together case for some medical components, or two interlocking halves of a portable radio. Why build two mating parts when you can make one? Redesign the snaps so that the halves can be fit together from either direction, thus building a so‑called "universal" part. Only one mould is needed, saving production expenses upfront. And you can now mould twice as many of one part, instead of half the quantities of two.
6. Modify and reuse moulds
It is relatively easy to remove metal from an existing mould. Adding metal, on the other hand, can be difficult or, for all practical purposes, impossible with rapid injection moulding. From the part perspective, you can add plastic, but you cannot take it away. Designing with this in mind is called "metal safe."
Some injection‑moulded parts go through multiple iterations until a final, workable design emerges. Instead of purchasing a new mould for every revision, a little clever planning will allow the same mould to be used multiple times. Starting with the smallest, most basic part design, mould as many pieces as needed, then re‑machine the mould to include additional part features, or a larger, taller version of the same part, and mould again.
7. Pay attention to DFM analysis
Every quote for an injection‑moulded part at Konlida is accompanied by a free design for manufacturability (DFM) analysis. This identifies potential problem areas, or opportunities for design improvement. Insufficient draft angles, "un‑machinable" features, impossible geometries – these are just a few examples in which part designs can and should be improved before clicking the "accept" button. Be sure to review these suggestions thoroughly.
🔗 Related: Design for Manufacturing Toolkit
8. Use a multi‑cavity or family mould
Maybe you are after a higher volume of parts? You can still achieve high volumes using aluminium tooling with two‑, four‑, or eight‑cavity moulds depending on size and part geometry that can reduce your piece part price, although this would impact your tooling costs.
Got a family of parts that all fit together? There is no reason to build a mould for each individual part, provided everything is made of the same plastic, each part is roughly the same size (have similar processing times), and all can be squeezed into the same cavity while still allowing for proper mould functioning.
9. Choose on‑demand production
Still another way to reduce moulding costs, depending on your part volumes, is to consider on‑demand manufacturing. This is a good fit for those who require slightly larger part quantities, typically up to 10,000‑plus parts from aluminium moulds. On‑demand production can be a great option to manage demand volatility, reduce total cost of ownership, and leverage cost‑efficient bridge tooling.
| Prototyping | On‑Demand Production | |
|---|---|---|
| Objective | Validate design | Flexible production of end‑use parts |
| Best when | Lifetime volumes < 2,000 parts Affordable tooling is important Production needed for ≤ 1 year |
Lifetime volumes > 2,000 parts Lower part price is critical Production needed for several years |
| Mould price | Lower | Higher |
| Part price | Higher | Lower |
Not sure which service is right? Get quotes for both to compare.
10. Consider part size
Always consider part extents – how big is the part, and will it fit comfortably in the mould while allowing for sprues, runners, ejector pins, and all the other considerations needed to make a mould work. Konlida's maximum part size for injection moulding is currently 480 mm × 751 mm with a maximum depth from the parting line of 101 mm. Larger parts require a larger mould, which may impact your mould and part costs.
11. Consider overmoulding
Depending on the part, overmoulding might cost more upfront, but could potentially save you money later. For example, overmoulding a gasket on a part upfront might be an added cost, but it can save costs later from having someone install a gasket manually.
🔗 Related: Overmoulding Guide
Final thoughts
Reducing injection moulding costs is not about cutting corners – it is about making smart design decisions early. The most expensive part is not the one with the most complex geometry – it is the one that fails in production, requires rework, or cannot be manufactured at the required volume.
A few hours spent reviewing your design for manufacturability can save weeks of tooling rework and thousands in production costs.