Tooling costs for custom heat sink extrusion - Page 1
Forum section: electronics / projects

author: m3g4by73
author_rank: Contributor
timestamp: June 18, 2015, 12:21:37 pm
content: Hi, just wondering if anyone here has ever had their own custom heat sink extrusion profile made up and what the tooling costs were like (ballpark figure)?I'm working on a project that will couple a thermoelectric cooler to the outside of a stainless fermentor with a block of aluminium and it will need to have a concave side that matches the OD of the fermentor. I had a prototype tooled up locally, but if we ever go commercial I'll be interested in having these mass produced to leverage economies of scale. I just don't know if this is the sort of thing you have done for only 100's of units, or whether you need to be a CPU manufacturer selling millions of heat sinks to make a custom extrusion worthwhile.

author: dom0
author_rank: Super Contributor
timestamp: June 18, 2015, 12:42:40 pm
content: You can get tools quite cheaply (well, you actually don't get them, the factory keeps them, usually), but with those you can't make hundreds or thousands of units and expect dimensional accuracy. That being said the lowest tooling costs for a small extruded heatsink will be in the range of 500-1000 $. Per unit cost will conversely be in the range of a few dollars.

author: DTJ
author_rank: Super Contributor
timestamp: June 18, 2015, 01:00:42 pm
content: It was a few years ago.... A guy I met needed a rectangular section aluminum extrusion about 100mm x 50mm with bowed sides. I recall thinking it was relatively inexpensive. The die as such did not cost him (it was part of the deal) but he had to buy a minimum weight of extruded section. It was $2000 or so, with inflation its probably $3k or $4k by now.

author: m3g4by73
author_rank: Contributor
timestamp: June 18, 2015, 01:10:34 pm
content: Thanks, these are all very useful responses. At least it sounds like it will be cheaper than our injection mould tooling costs. Milling may still be an option too as suggested.

author: senso
author_rank: Frequent Contributor
timestamp: June 18, 2015, 01:20:52 pm
content: Take a look into this:http://www.arachnidlabs.com/blog/2014/04/15/custom-manufacturing-in-china/

author: SL4P
author_rank: Super Contributor
timestamp: June 18, 2015, 01:21:49 pm
content: The questions you may need to ask are the MOQ of the extruded product, and shipping costs.I had a toolset made about 5-6 years ago, and MOQ was 100 metres of extruded product.The best price and turnaround was China (of course)...I provided AutoCAD drawings - which they re-drew for some reason... within the $1k approx tooling and setup charges. Non-recurring charge for future production runs.Shipping was cheap enough, but the rate of import duty, and land transport from the local port to my place in the same city was an added surprise!All in, it was well worth it, as I was able to sell off excess length from each factory order as it was a useful profile!

author: hayatepilot
author_rank: Frequent Contributor
timestamp: June 18, 2015, 01:32:20 pm
content: Aluminium extrusion profile tooling is relatively cheap. It ranges from 500-5000$. (Source)Since your Heat sink is relatively simple (solid profile, no cavities) I would estimate the cost around 1000$. But don't quote me on that.In addition to the tooling cost there can be a minimum orderin weight (maybe around 500kg) depending on the manufacturer and the press used.Greetings

author: m3g4by73
author_rank: Contributor
timestamp: June 19, 2015, 10:11:05 am
content: Quote from: senso on June 18, 2015, 01:20:52 pmThanks for the awesome link. I love it when these kickstarter guys blog their trials and tribulations.

author: eas
author_rank: Frequent Contributor
timestamp: June 20, 2015, 09:47:19 pm
content: Quote from: m3g4by73 on June 19, 2015, 10:11:05 amYou might also want into the issues the OpenBeam guy had with getting suitable quality on their aluminum extrusions.

author: rx8pilot
author_rank: Super Contributor
timestamp: June 20, 2015, 10:15:26 pm
content: I have done a few projects where the tooling was in the range of $750 - $1500 but the cross sectional area was rather small. The costing elements are design cross section area measured withe a circle. Internal holes require separate pieces of the drawing tool. Tolerance required - tight tolerances can add up.I used SAPA do do the work on my projects which were all very low volume of about 1000lbs. Most manufacturers don't want to even talk about less than that.

author: nctnico
author_rank: Super Contributor
timestamp: June 21, 2015, 10:50:37 am
content: It might make more sense to have an existing heat sink milled. For optimum heat transfer the surface must be smooth. Extruded heatsinks are not very smooth so the higher end ones are always milled to have a smooth surface.

author: rx8pilot
author_rank: Super Contributor
timestamp: June 21, 2015, 07:14:07 pm
content: I do not believe that is true at all. The more surface area, the more it transfers heat to the atmosphere. Many heat sinks, for this reason, have ribs which are relatively easy in extrusion manufacturing and very difficult to mill. I have personally designed and CNC milled lots of heats sinks for commercial applications and it was very slow and expensive.I needed special tools, fixtures, and cooling to make them happen. In the end they looked amazing, but were only suitable for very high-end cost is no object applications. For a medium size heat sink, I would start with a 4lb block of aluminum that costs $12. Then I would spend an hour milling all the slots slowly. As it is milled it loses strength and starts to vibrate. This requires very special attention to every detail of workholding, tooling, tool path, speed, feed, and cooling to pull it off. Our cost after it was all said and done was $100-$150/ea. Add some profits and VERY few people want it. Same size and performance in extruded was about $5ea and $10/ea after drilling mounting holes.

author: nctnico
author_rank: Super Contributor
timestamp: June 22, 2015, 12:01:19 am
content: Quote from: rx8pilot on June 21, 2015, 07:14:07 pmThat is true for the end that dumps the heat into the atmosphere but you also need to get the heat into the heatsink and for that you need 2 surfaces which are as smooth as possible for optimal heat transfer. Don't think for a second that thermal paste is a good conductor of heat! It is just better than air stuck between a device and a heatsink but still a lot worse than a good direct contact between the surfaces.

author: rx8pilot
author_rank: Super Contributor
timestamp: June 22, 2015, 01:11:22 am
content: In a theoretical world a purely and perfectly mated mechanical mate between device and heatsink is good. Practical reality - it never happens and there is always a benefit to a thermal interface material to improve contact/transfer. For low $ situations, there is almost always some synthetic and soft interface material on 'mill finish' extruded heat sinks. For aerospace or high-end computing there are prepared surfaces that are machined, ground, or polished but they still use a void filling thermal interface.Facing the flat side of an extrusion would help improve thermal transfer a little bit over using paste or thermal pads and is FAR easier than making a heatsink from a solid block of material. In reality, if you are that close to the edge, the component choice should be re-considered.

author: calexanian
author_rank: Super Contributor
timestamp: June 22, 2015, 05:41:51 am
content: +1 for relatively inexpensive tooling, but you need to take a minimum amount. Typically it's a minimum weight and that will determine the minimum linear length of product. Some mills will also offer finnishing such as cutting, drilling holes, and don't forget anodizing. I looked into it and it was a 300 pound minimum and there were about 2k in tooling costs, but it was a hollow part (more expensive tool)

author: peter.mitchell
author_rank: Super Contributor
timestamp: June 22, 2015, 06:58:34 am
content: It may be significantly cheaper to use a COTS heatsink and get a custom made adapter plate to add a concave surface to the bottom of the heatsink.The adapter would be a very simple and cheap part and the COTS heatsinks would be cheap because they are already mass produced.