[skippy]

Hi Mike,
As you can see I put a fair bit of time into that answer thinking that you were a "back-yard-wanna-be" (home brew hopefull??) of which there are plenty in manufacturing, or at least a small operation however that's clearly not the case so sorry about that. I drew my conclusions too fast. Certainly fitting that type of led in an automotive application never been done so no wonder you're excited about it. You'll probably get sued for blinding the drivers behind said bikes! hehehe

Punching for me would be the way to go both on the aluminium heat sink and also the circuit board external shape which I assume will be what holds everything together and also ties it to the body of the light which I assume is plastic.

The only problem I see is that after punching you'll have a jigsaw of pieces and then you must find all the pieces, orientate them and bond them in perfect alignment on the substate. Yes jigs can help but I wonder if it wouldn't be better to punch as suggested above but leave two narrow little bridges on each piece to hold it all together, bond it, place in mill to remove bridges. However that makes one more process so I don't know, just an idea..... I'll think on it a bit today.

[lerman]

Year (well, actually decades) ago, when I worked at Grumman, they used a process referred to as "chem milling" to "machine" aluminum sheet.

That was a chemical process to remove mass from aluminum.

I would think that you could bond your aluminum sheet to the pc board material, apply resist, and then etch it in place (in much the same way as a pc board is etched) with the proper chemical. My guess is that lye (sodium hydroxide) would work well. That assumes you can find an appropriate resist.

Ken

[Scott_bob]

Can this even be stamped?
Aren't those outlines 1/2 way thru the material?

If you get a quote for stamping or fine blanking, you'll be shocked...
Granted the cost will be low per piece, after you pay for the die but not for quite awhile.
You're not going to recover your cost (of a die) till after 10k pcs (at least).
IMO, you need higher RPM. Buy a reasonable high speed spindle for your low RPM performance CNC, say NSK pneumatic 40,000 RPM...
Invest in a vacuum system, nest your parts as many as can fit on your vacuum fixture, and yah, run it unattended!
Get some help here on what it might take to automate broken tool detection after every part and let it go... Overnight...

Have fun,

[Mortek]

We hot glue ceramic strips to a plate for grinding. I think this method would work well for this application. Make a fixture plate out of say 1/2" aluminum. Put on a hot plate to heat. Use a clear glue stick and spread out on fixture plate. Place your .020 sheet on the fixture plate with a weight on it and remove from the hot plate. Allow to cool and then go place it in your mill and cut away. You could make up several fixture plates and be mounting more as you are waiting for one to cut. Put back on the hot plate and remove the finished part. Soak in acetone to remove the glue residue and you have a perfect part. Believe me I was shocked at how well this works. I'm certain it will work for you.

Here's a hot plate like we use for sale on ebay.
http://cgi.ebay.com/ws/eBayISAPI.dll...=WDVW&tc=photo

You can get larger hot plates

[ViperTX]

Does Waytek sell these LED taillights??? I know they have a line....

[skippy]

Mike, I have a fair bit of product manufacturing experience under my belt but I always tend to trust Bob_scott's opinion more than my own when it comes to process/method cost/time advice. If you stick with the present process, the multiple part vac fixture using high speed spindle seems to me to be the logical way to go both in time and cost keeping in mind the relatively small numbers you are talking about. (I mean it's not a 10k run in one hit)

However that still doesn't address the jigsaw puzzle alignment problem you will be faced with at the time of bonding the pieces to the pcb. In my humble opinion, this will be as bigger challenge as the problems already discussed in this thread. I know you said you are working on this in conjunction with the lumiled engineers and I don't profess to know more than you or the lumiled engineers HOWEVER, don't be afraid to think outside the box either. Í my not come up with an answer here but just some thoughts and a bit of encouragement to do some lateral thinking.

I think I know the style of emitter you are working with and if I understand correctly the base of the emitter connects to the heat sink via thermally conductive epoxy. The base of the emitter and the heatsink are not connected to the + or - voltage (i.e. they're isolated). You only need the channels so that the heatsink "will not touch any exposed traces on a circuit board" From this we can deduce that the circuit board is probably a single sided FR4 board with the copper tracks facing the side of the emitter.

So, what would happen if you made your circuit board the other way around, i.e. with the laminate facing the other side (i.e. facing the front of the bike). This would mean that the heat sink could be one piece and wouldn't need channels to be cut (= better heat sinking for the LEDs) and would therefore only need the external shape to be cut plus simple holes (or slots) where the terminals connect to the pcb. A substantially bigger cutter could be used as a result. Next is to bond the heatsink to the fibreglass side of the prepared pcb, finally bond and screw emitters to heatsink/pcb. Or perhaps you were planning to use a double sided pcb? If that's the case, (a) just redraw the board so that it is single sided with some jumpers if need be or (b) use a second small pcb board piggy backed to the first or (c) a double layer board. Personally I'd imagine that option (a) should be possible.
If this method is possible, your pcb will have holes already drilled where the emitter attaching screws will screw to the pcb and your heatsink will have somewhat bigger holes in the same location. (bigger so that the terminals don't make contact with heatsink) You then use the two most opposite holes to fix (+ align) heatsink to pcb during the bonding process. You would use a step shanked screw for this assembly process. In saying that, I wonder if the heatsink has to bonded to the pcb anyway? I'm thinking on the run here. Pcb with 2mm holes for 2mm screws/nuts (sorry I can't talk in fractions of an inch), 3mm holes in heatsink where emitter terminals attach, step shank plastic washers so that current is transmitted from emitter terminal to pcb without making contact with heatsink. These screws also serve to hold heatsink to pcb.

EDIT Another variation on the above would be: instead of starting off with the boomerang looking piece cut from sheet aluminium, get it die cast in alloy complete with the terminal mounting holes already in place, plus a slight recess to position/accept the body of the emitter (= faster assembly time) and possibly a little pin at each end of the boomerang to line up with corresponding holes in the pcb to make for faster positioning during assembly with pcb. I'd also imagine that the board doesn't have wall to wall emitters so you therefore use up the left over real estate with traditional cooling fins to once again increase cooling.

EDIT2 Up until now, I've (we've?) been assuming that the pcb is the central piece of this project because the emitters and heatsink/s are fitted to it and it's the pcb that is screwed to the body of the light. (i.e. pcb acts as the mounting plate or fixture). I may be wrong but this is what I've been assuming. Now, following on with the one piece die cast heatsink idea. What if the heatsink becomes the central piece? i.e. the heatsink is what mounts to the plastic body of the light and also holds the pcb and emitters?

The heatsink would have all the previous features plus the holes or tangs or whatever is used to fit to the plastic body of the light. The same step shank plastic washer system would be used for the terminals of the emitter HOWEVER the pcb would use stand-offs and if a double sided pcb is to be used, it would depend on which side of the pcb you put your plastic or metal washers. The added advantage of this is the +/-2mm air gap between the heatsink and the pcb which will increase cooling even further. My whole reasoning here is based on my assumption that maybe not all, but certainly the majority of heat is dissipated from this type of emitter via the flat underside (of the emitter). If this is not correct, please let me know and I'm sure we can still come up with something.

EDIT3 Another thought occurred to me during the night, if for whatever reason the one piece cast heatsink isn't possible, what about if you mill a heatsink as per your picture BUT mill it from the pcb side not the emitter side and you cut the external shape, holes, and slots to full depth but only cut the tracks half way through using a bigger cutter (= faster). This would keep it as one piece (= faster = cheaper) and because the tracks are wider, alignment so that heat sink doesn't touch pcb tracks becomes a non-issue. Even if you increased the material thickness slightly so that milling half way through was easier, this method would eliminate the jigsaw problem plus greatly improve the heatsinking ability of the system. (in case you don't understand that statement, say you have 3 +3 blinkers, 5 for the stop/tail light = 11 emitters in total. If stop light is activated, 5 emitters will be dissipating heat to the total area of the heatsink instead of each just having it's own little heatsink.) Using any of the above methods makes it unnecessary to use MCPCB which you may or may not have been thinking about using.

Well what do you think? As you can see, this one's had me thinking and as I said earlier, maybe none of these will be the answer but I'm at least trying to broaden the possibilities.

[gar]

050605-0712 EST USA

fastturbovet:

Copper has about twice the thermal conductivity of aluminum. There is also thermal resistance in the bond from the pc board copper to the aluminum heatsink.

In any event if copper was used for the heatsink material, then you would need about 0.010" thickness.

You might investigate the pc board processing and see if the vendor could copper plate 0.010" copper in the heatsink areas. If so it might solve many problems.

.

[skippy]

"Copper has about twice the thermal conductivity of aluminum." True

"There is also thermal resistance in the bond from the pc board copper to the aluminum heatsink." If Mike chooses the heatsink bonded to the circuit board route, I'd imagine he'll be using thermally conductive epoxy which although it does have some thermal resistance, overall is pretty conductive.

"You might investigate the pc board processing and see if the vendor could copper plate 0.010" copper in the heatsink areas. If so it might solve many problems" I still maintain that if he separates heatsink from circuit board with an air gap of say 2mm, it will mean that the heatsink will do its job to get rid of heat (and more efficiently because both sides of the heat sink will be exposed to air) and the expensive circuit board and microcontroller can be kept away from the heat source.

Gar, I think your idea of plating the pcb is a good idea but I'm just saying that maybe a bit of lateral thinking is required.

p.s. I looks at though Dave's not the only one that has left the room. Mike has too!

[fastturbovet]

"Copper has about twice the thermal conductivity of aluminum." True

"There is also thermal resistance in the bond from the pc board copper to the aluminum heatsink." If Mike chooses the heatsink bonded to the circuit board route, I'd imagine he'll be using thermally conductive epoxy which although it does have some thermal resistance, overall is pretty conductive.

"You might investigate the pc board processing and see if the vendor could copper plate 0.010" copper in the heatsink areas. If so it might solve many problems" I still maintain that if he separates heatsink from circuit board with an air gap of say 2mm, it will mean that the heatsink will do its job to get rid of heat (and more efficiently because both sides of the heat sink will be exposed to air) and the expensive circuit board and microcontroller can be kept away from the heat source.

Gar, I think your idea of plating the pcb is a good idea but I'm just saying that maybe a bit of lateral thinking is required.

p.s. I looks at though Dave's not the only one that has left the room. Mike has too!

I'm still here.

I appreciate the thoughts and ideas on how to do the product, but really, I am already decided on how it will be made. The problem is that there are many many design considerations involved here, which include the equipment we have available, cost of parts, fabrication time, packaging constraints, LED specifications, PCB packaging requirements, external component setup and many other things. I have spent quite a lot of time on the design of this light, along with lots of other folks and this is the best solution. I can't go into explicit detail on each aspect of the design, partly due to it being proprietary info, but also because I am not looking to design a new product as a group - it's already designed and it will be made in the way it has already been designed. I sincerely appreciate the input, but really I am not looking for a way to design the product - that part is done, what I need is the best solution to produce the metal plate pictured. The LED's being used are not the type that has a thermal pad on the bottom, and the heat sink is a conductor for the power and ground in addition to being a heat sink. There are so many different aspects of the design, including the temperature range, installation requirements, vibration resistance, LED cost, other parts cost, cost of consumable materials and so many other factors that approaching the design from a different standpoint is really not helpful and I can't give out every piece of data that led us to this design, but suffice it to say there are a lot of smart and knowledgeable people involved and this design is the best way to go, given the parameters at hand.

I hope that doesn't sound rude - I really appreciate the enthusiasm from folks about this project, but the critical thing is quickly producing the part at hand.

I have had pretty good luck machining them on our CNC mill. I have played around with feeds/speeds and gone from a HSS bit to a solid carbide with good luck. I am cutting dry, and using double-sided tape to hold the AL sheet to a piece of dense/hard 2" foam which I clamp in the vice. This is workign well. The hardest part is that it's a PITA to remove the tape after the cut, and it needs a new piece of foam cut every time and mounted.

Thanks to the previous poster for the hot glue suggestion - I am going to give that a shot. I have tried spray-on contact adhesive but it seemed to gum up the bit and cause it to heat up and break. The tape is messy but isn't causing breakages. I think the hot glue idea may be the best so far - any other ideas on holding down the piece? I have looked into stamping, chemical etching, laser cutting, waterjet and blanking and they are all more expensive over the expected product lifespan. Problem is, since its a motorcylce part, they change so quickly that I would never get the ROI from stamping, and laser/waterjet is too $$ per part compared to milling. I can run the mill unattended and fit 9 of them on the table at once, run if 3-4 times a day if need be, once overnight and do 40-50 a day no problem. I need about 100 a month to start so no worries.

[Scott_bob]

An alternative clamping method...
I have used this and it does work well, it's just a bit messy like the double stick tape.

Well worth a try though, a lot less work. Just heat, cool and you're ready to cut, then heat again to melt the adhesive. Works well.

http://www.miteebite.com/
(then click to the mitee-grip)

Good luck,

[skippy]

Hi Mike,
Thanks for filling us in a bit on what's what and no it wasn't rude in the least and yes we all realise that one can't publicise every little detail about a product otherwise someone else will be making it before you do.

I now understand why the heatsink can't be made in one piece ("the heat sink is a conductor for the power and ground in addition to being a heat sink")

One thing you didn't answer is the question about how you are going to take all the jigsaw pieces and bond them to the pcb with correct alignment. Sounds time consuming even with a jig? Did you give any thought to (at least I think I mentioned this idea earlier) cutting the outside shape of the aluminium with perhaps two holes that coincide with the pcb, bond ali to pcb using your thermally conductive epoxy (if that's what you're going to use), then mill out the grooves of the heatsink. This would solve a lot of problems. It would be very easy to do if you are using single side FR4 and yes you may have to true the squareness of your mill first but even if you are planning on using a double sided pcb I still think this would work as you'll have the thickness of the epoxy as a safety margin. I've milled to this tolerance previously simply by making the multiple part, vac hold down set up discussed earlier in the thread.

Failing that, as mxtras says: post-prototype, stamp it and get some sleep

Your mates here at cnczone only ask one favour, send us a post card from the Carribean Islands when you get rich and retire there ok? hehehe

[JavaDog]

suffice it to say there are a lot of smart and knowledgeable people involved and this design is the best way to go

Too bad they didn't figure in the manufacturing issues into the design...

Mortek, the hot-glue idea is slick. Going to have to remember that one myself! Have you ever had the heat from machining re-melt the part though?

[Mortek]

nope, always using coolant though. That should stop it on the thin sheet.

[fastturbovet]

Hi Mike,
Thanks for filling us in a bit on what's what and no it wasn't rude in the least and yes we all realise that one can't publicise every little detail about a product otherwise someone else will be making it before you do.

I now understand why the heatsink can't be made in one piece ("the heat sink is a conductor for the power and ground in addition to being a heat sink")

One thing you didn't answer is the question about how you are going to take all the jigsaw pieces and bond them to the pcb with correct alignment. Sounds time consuming even with a jig? Did you give any thought to (at least I think I mentioned this idea earlier) cutting the outside shape of the aluminium with perhaps two holes that coincide with the pcb, bond ali to pcb using your thermally conductive epoxy (if that's what you're going to use), then mill out the grooves of the heatsink. This would solve a lot of problems. It would be very easy to do if you are using single side FR4 and yes you may have to true the squareness of your mill first but even if you are planning on using a double sided pcb I still think this would work as you'll have the thickness of the epoxy as a safety margin. I've milled to this tolerance previously simply by making the multiple part, vac hold down set up discussed earlier in the thread.

Failing that, as mxtras says: post-prototype, stamp it and get some sleep

Your mates here at cnczone only ask one favour, send us a post card from the Carribean Islands when you get rich and retire there ok? hehehe

You're right! Aligning them was a bit of a PITA

What I have done is all those little parts you see in the pic I posted have "ears" that connect them. Basically little half-circles that connect each segment to the one on either side of it. As you can see the part has holes (and so does the PCB). So I have made a jig which is just a sheet that I can place a bunch of the PCB's on with pins extending through the holes. I lay the PCB's on it, then I put it in our auto-dispensing machine which splurts out conductive epoxy, then each heat-sink sheet is layed down on top over the pins which precisely aligns it on the PCB. I put another sheet on top which is basically a weight and put it in the over to set the epoxy. Then it goes back on the dispenser which puts more epoxy on to bond the LED's.

CHeck out this pic



I control each LED individually so they cannot be connected together. The OEM of the LED's provides a punch/crimp method for attachment, but the machine to do this is many many tens of thousands of dollars, and since it deforms the metal mount, is not suitable for our use (since we need it to be flat for the bond procedure). You can see in the picture the remnants of the metal "ears" that connect each segment. This is a rough prototype so they were hand-cut to test this prototype board. In the actual implementation, after the LED's are bonded and heated to set the glue, the fixture plate is re-mounted in the CNC and the ears are milled off, producing the board.

hope this clarifies what the application is!

The suggestions on machining the sheet have been excellent, I bought a hot-plate and will give the glue method a shot!

[fastturbovet]

Too bad they didn't figure in the manufacturing issues into the design...

Actually, they did. If you have a better idea, I am all ears.... but if you don't understand the application, how can you say that the manufacturing issues were not addressed? The question was not "hey can anyone tell me how to make this product" but rather it's already been spec'd and the task at hand is the best method to cut the board. I can run a batch of these now - totally unattended. My issue has been holding down the work correctly. Right now I use double sided tape which works, but is a pain to clean off (although I can just soak in acetone and it's unattended).

I have the tools I have at my disposal. The constraints are that it must be cost effective as my final price is already determined because of my contracts with distributors. There are many ways to solve the problem - using a different LED would be one way, but there are also constraints on the lens which requires discrete point sources of light. I can use something like a 1W+ emitter but the price isn't there and they output too much light for what I need. I know the electronics side of it *very* well and there is nothing that compares in price/performance to what we're using. Production is more difficult than our other products, but at least its mostly automated, so the hands-on time for production is less than most of our stuff.

If my design does not take the manufacturing issues into account, I am sure you could do it better and kick my butt in the marketplace! We sell many thousands of these products a year, so the money is there... and with a superior design at a better price point, I couldn't compete. I'll wait to see your superior design in stores around the USA, yes?

No flame intended, but it's hella presumptuous to think we're idiots who didn't think of what it takes to make the product (since the cost to manufacture comes outta my own pocket)

[fastturbovet]

Your mates here at cnczone only ask one favour, send us a post card from the Carribean Islands when you get rich and retire there ok? hehehe

Skippy,

Well, working for yourself is all about being rich right? I know when we (my and my biz partner) started this company about 5 years ago, we instantly became right and have been trying to find the time to spend those millions! Haha... well, maybe not. What are you doing in terms of CNC/electronics? I would be happy to give you lots of details on what we do, if you're interested, didn't mean to sound snippy prior, just I have a deadline and need to get this cranked out. I could talk electronics/software/machining all day long! We started back in '99 with an idea for a bike part... I sold all my "toys" I had accumulated over the years, rented office space and got to work. First couple of years were VERY hard... but it paid off. If I had a buck of every time I sat in a cheap hotel room at some trade show in some city thousands of miles from home after working a 15 hour day (the third, fourth or fifth in a row!) I'd be rich already. We stuck it out for the first couple of years and the business grew and grew. Now the problem has been finding the time to do production as well as finding time to get new ideas off the ground. I don't have to worry about paying the bills anymore (thank god) but it's still a challenge finding time to work on new stuff.

I can say the BIGGEST factor in our success has been being resourceful about getting the job done. You'd probably laugh if you saw some of the machines we make parts on... been replacing it with more high end stuff but I'm proud of what we accomplished. Hell, I have a pick-and-place machine we paid $800 for and retrofitted our own CNC control on, the Bridgeport (which I posted about on here) that I got for $1300 and my partner built a whole CNC control for it, the epoxy dispenser that I machined a mount for a rotozip to make it into a CNC router, and on and on. Its fun though and sure as heck beats working for "the man"

[skippy]

Hi fasturbovet, unless I'm mistaken Javadog wasn't criticising you but instead saying that the led manufacturer sure is making you work for it due to their design.

The "ears" system above is what I was talking about when I said "I wonder if it wouldn't be better to punch (or mill) as suggested above but leave two narrow little bridges on each piece to hold it all together, bond it, place in mill to remove bridges. However that makes one more process so..... "

"Well, working for yourself is all about being rich right?" No, I was just joking. For me, the greatest "buzz" is the challenge, particularly of developing a new product, then seeing it go into production, and then seeing that product in use (in your case on someone's bike). I have always believed that it's the love of doing it that comes first (no matter if you're selling real estate, manufacturing something or providing a service) and from there success is almost guaranteed and the money is a natural follow on from success.

Neat product, all the best with it and I'll pm you re the other.
p.s. someone should start a thread about where each person's avitar came from. I'm sure there'd be some interesting stories. Yours, well that's obvious but howboutapicy, please?

[JavaDog]

Hi fasturbovet, unless I'm mistaken Javadog wasn't criticising you but instead saying that the led manufacturer sure is making you work for it due to their design.

Glad someone understood that. Just seems they they don't make that particular product easy to integrate...or maybe it was just the way it needed to be integrated in your design that made it tricky. Either way, good to see you worked it out.

FYI, if I had wanted to call you an idiot - I would have. Honestly, I hope I am half as succesful as it sounds like you guys are when I start getting my ideas off the ground. Kudos for making it work.

[fastturbovet]

"Well, working for yourself is all about being rich right?" No, I was just joking. For me, the greatest "buzz" is the challenge, particularly of developing a new product, then seeing it go into production, and then seeing that product in use (in your case on someone's bike). I have always believed that it's the love of doing it that comes first (no matter if you're selling real estate, manufacturing something or providing a service) and from there success is almost guaranteed and the money is a natural follow on from success.

Neat product, all the best with it and I'll pm you re the other.
p.s. someone should start a thread about where each person's avitar came from. I'm sure there'd be some interesting stories. Yours, well that's obvious but howboutapicy, please?

I was just joking about the being rich part... I laugh about it because everyone who hears you started your own outfit thinks "wow you must be rich", but if only they knew As we know, we are the LAST ones to get paid! At least I got a chance to see the world (through the murky windows of cheap hotel rooms and 5 hours of sleep a night)

Your idea of the mounting ears is a good one, I can say its working well on the finished product. Skippy I will post another pic in a minute so you can see the brightness level. Are you familiar with the type of LED on that board? They are desigend for automotive use but not to be used in the way we're using them... when I first talked to Ken at Lumileds he thought I was nuts, but over the past few months they have gotten pretty interested in this particular usage and its working great. The biggest hurdle was "how do you take and LED that's designed to be crimped onto a substrate in groups in a no-heat forming process, and use it on a PCB board where everything is reflowed". But I enjoy the challenge as well, so I am usually having fun doing this stuff.

Check out the pic I'll post - the LEDs are *bright*. P.S. If you ever need any LED's, let me know. I buy a bunch of 'em and I have really good relationships with most of the manufacturers. You can even get the Lumileds 24lm emitter for $0.85/ea now! They have a new white emitter coming soon for headlight applications. Confederate motorcycles is incorporating it into their 2005 MY headlights - cool stuff!

[fastturbovet]

Glad someone understood that. Just seems they they don't make that particular product easy to integrate...or maybe it was just the way it needed to be integrated in your design that made it tricky. Either way, good to see you worked it out.

FYI, if I had wanted to call you an idiot - I would have. Honestly, I hope I am half as succesful as it sounds like you guys are when I start getting my ideas off the ground. Kudos for making it work.

Sorry if I came back a little harsh, you are right, this particular LED is not originally designed to be used this way. The problem with high-power LED's is they decrease the thermal resistance to the LED die which means they run cooler for a given amount of heat and conduct it away from the die very efficiently, but it also means they either can't be soldered or they require big heat-sinks to a non-conducting pad on the LED. THis particular one was designed for mounting to a metal board in a crimp/punch process but it didn't suit our needs. Our options were super-expensive LED's that were too bright, or clusters of cheaper ones. The clusters screw up the optics in the light and don't end up being cheap when you add them up, so our challenge was to take an LED with a very good cost/brightness ratio but use it in a way other than it was designed for. If we could solve that challenge, we could overcome our biggest obstacle the past year, which was cost, brightness, and function. That's what this product is designed to do, and it was a major PITA to get it all working right... but with a lot of trial and error, haggling, and the resourcefulness of some great minds it was able to be done, and I am saving money over my previous cost on lesser-brightness products. The only problem is the time it takes to cut these aluminum bits, and the fixturing of them. Time is not a huge big deal, I can run 'em and walk away. The fixturing is not a huge deal, and the suggestions here have helped a ton.

It would be a good idea to start a business forum on this site, I think, for discussion of making money with your CNC setup.