3 ms·

You are significantly underestimating the cost of producing molds. You could easily hit $100k for molds made in the USA, $10-20k made in China. That’s also assu

by conk 6y ago

You are significantly underestimating the cost of producing molds. You could easily hit $100k for molds made in the USA, $10-20k made in China. That’s also assuming you get the molds right the first time and don’t have to go back and make new ones. Plus there is the setup and minimum production runs, you need a fairly large demand to make producing these viable. 2-3 of these ($680-$1020) doesn’t cover cost just to modify the design to work for injection molding.

bfieidhbrjr 6y ago
I've found the same thing. Dumb question, why is the cost so high? Is it people costs or what?
- cfraenkel 6y ago
  To make enough shots for a low unit cost, the mold has to be made of very hard steel. So that takes a long time on a very expensive cnc. If you make it out of softer material to make the mold less expensive (ie aluminum), you only get ~100s shots or so. Good enough for testing / beta runs, but not enough to amortize the engineering & cnc costs.
  - icegreentea2 6y ago
    Prototype tooling can sometimes (depends on your part obviously) get you up to the 1-10k range of shots now. At that range, it can be sufficient for certain types of product runs.
- analog31 6y ago
  I've worked in the molding industry. First, the mold has to be designed. This involves planning for the flow of molten plastic through the passages and cavity of the mold, venting of air, often re-design of the part so it can be effectively molded, etc. Shrinkage as the part cools affects how multiple parts fit together. That's huge for consumer products. There's CAD software for doing this, but it still requires an expert to know how to use it. Second, the mold itself is made of a very hard steel, though there are cheaper "soft tooling" materials for making lower quantities before the tool is worn out. The special steel may require special machining processes. The tool also has a variety of moving parts such as ejector pins and other mechanisms if the part is not shaped to be ejected cleanly. If the mold comes from low-cost supplier, there's the added cost of reworking it in order to iron out minor problems. I spoke to one tool-and-die machinist who told me most of his income came from repairing cheap molds. If you save on the mold, you often pay more for the pieces due to scrappage, difficulties setting up the molding machine, or the short lifespan of the mold. Right now I work in a business that makes expensive high-tech equipment, so we can afford to eat the cost of making expensive parts from expensive molds. For prototype quantities, we tend to prefer things like folded sheet metal, CNC, and even small aluminum castings with secondary machining processes. In that milieu, the cost of 3d printing is actually quite competitive. I just got some pieces costing about 1000 bucks each, but they were delivered to my doorstep a few days after being designed. Also: Something I've learned is that everything I know might be wrong tomorrow. Every manufacturing process is being steadily improved, and a process that you wrote off as being too expensive might have suddenly become cheap for reasons you're not aware of. Always ask.
  - bfieidhbrjr 6y ago
    Thanks. I find this whole area fascinating. It feels like if there was a way to make molded parts cheaper it would open up a large gulf in between "$300 3d printer" and "$15k for one mold and BTW you need 5 molds for your thing". I do a lot of 3d printing but have run in to the limits quite a few times where I want something bigger than my print volume allows, or I want something water proof, or food safe, or I want something transparent (which can also be used outside), or I want it smoother... resin printing or finding someone with a big printer... these things help sometimes. Another trick I have yet to succeed at is using some existing plastic part, or transparent plastic from a soda bottle... Repurposing for these edge cases.
    - analog31 6y ago
      Memorize the McMaster-Carr catalog, which is like the Python Package Index of mechanical things. ;-)

by conk 6y ago

bfieidhbrjr 6y ago

I've found the same thing. Dumb question, why is the cost so high? Is it people costs or what?

cfraenkel 6y ago
To make enough shots for a low unit cost, the mold has to be made of very hard steel. So that takes a long time on a very expensive cnc. If you make it out of softer material to make the mold less expensive (ie aluminum), you only get ~100s shots or so. Good enough for testing / beta runs, but not enough to amortize the engineering & cnc costs.
- icegreentea2 6y ago
  Prototype tooling can sometimes (depends on your part obviously) get you up to the 1-10k range of shots now. At that range, it can be sufficient for certain types of product runs.
analog31 6y ago
I've worked in the molding industry. First, the mold has to be designed. This involves planning for the flow of molten plastic through the passages and cavity of the mold, venting of air, often re-design of the part so it can be effectively molded, etc. Shrinkage as the part cools affects how multiple parts fit together. That's huge for consumer products. There's CAD software for doing this, but it still requires an expert to know how to use it. Second, the mold itself is made of a very hard steel, though there are cheaper "soft tooling" materials for making lower quantities before the tool is worn out. The special steel may require special machining processes. The tool also has a variety of moving parts such as ejector pins and other mechanisms if the part is not shaped to be ejected cleanly. If the mold comes from low-cost supplier, there's the added cost of reworking it in order to iron out minor problems. I spoke to one tool-and-die machinist who told me most of his income came from repairing cheap molds. If you save on the mold, you often pay more for the pieces due to scrappage, difficulties setting up the molding machine, or the short lifespan of the mold. Right now I work in a business that makes expensive high-tech equipment, so we can afford to eat the cost of making expensive parts from expensive molds. For prototype quantities, we tend to prefer things like folded sheet metal, CNC, and even small aluminum castings with secondary machining processes. In that milieu, the cost of 3d printing is actually quite competitive. I just got some pieces costing about 1000 bucks each, but they were delivered to my doorstep a few days after being designed. Also: Something I've learned is that everything I know might be wrong tomorrow. Every manufacturing process is being steadily improved, and a process that you wrote off as being too expensive might have suddenly become cheap for reasons you're not aware of. Always ask.
- bfieidhbrjr 6y ago
  Thanks. I find this whole area fascinating. It feels like if there was a way to make molded parts cheaper it would open up a large gulf in between "$300 3d printer" and "$15k for one mold and BTW you need 5 molds for your thing". I do a lot of 3d printing but have run in to the limits quite a few times where I want something bigger than my print volume allows, or I want something water proof, or food safe, or I want something transparent (which can also be used outside), or I want it smoother... resin printing or finding someone with a big printer... these things help sometimes. Another trick I have yet to succeed at is using some existing plastic part, or transparent plastic from a soda bottle... Repurposing for these edge cases.
  - analog31 6y ago
    Memorize the McMaster-Carr catalog, which is like the Python Package Index of mechanical things. ;-)