Reply With QuoteWould be good if they could make a 5-6 meter hull this quick the cost would be really cheap there would be a big market for it
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Came across this link, thought you guys might be interested, unfortunately you may need a million or so just to setup the plant before you can make one.
https://s3-us-west-1.amazonaws.com/h...at_molding.mp4
Would be good if they could make a 5-6 meter hull this quick the cost would be really cheap there would be a big market for it
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That's called "blow moulding" like how cheap cases for power tools and stuff are made, the item must be hollow, Polycraft boats are kind of similar, but I think they are "roto molded" which is a different process, but still only takes a jiffy to make a complete item.
Its quiet interesting i know the molds cost a huge amount of money in the hundreds of k's but if these little dingys are made that quick how come there sale prices are similar to tinnies that take time to weld up
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Probably because a decent welding machine only costs less than $6000, a days labour, several hundred of dollars for the ally and consumables, VS a $1M plus for the machinery and dies/molds, the cost of the plastics and heating it up. So the owner would have to make a gazillion of them just to recover his startup costs without even making a profit.
Then once you add taxes, delivery, distributor markup, boat sales yard markup , insurance etc. etc. the price of a boat , (doesn't matter if it is ally or plastic) has skyrocketed. But at the end of the day the buying public decides, if they perceive that the item is worth the asking price and if they are willing to pay that sort of money for a plastic boat VS an Ally one, they all have the pros and cons.
So if it takes them 5 minutes to make the boat and they produce a heap of them in a run, they they have to store them and until the inventory runs down again that $1M plus bit of equipment just sits there doing nothing and not earning it's keep.
Yeah but Ed 6k welder plus all those other cost materials etc.. it adds up and its mostly consumables
With that 1mil mold how long do they generally last? As tinnies havent really changed much in 50 years lets say u use that mold for the next 50 years surely its going to make a absolute ton of dinghys
Where as the bloke with the welder would have gone thru x amount of machines over that time
I can actually see where the money goes into tinnies as its all hands on
But the plastic dinghy wham bam out the door gone.. now i donno how a metal mold is made i can only think cnc milling maybe a weeks work? Could it really cost 1mil to make such a mold?
Could they possibly use a box with melt proof molding material to shape the hull and just cast the mold?
I'd love to hear how they actually do it
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There also the other equipment involved with it, it is not just the molds, it also the heating/regulating system, the feeder, the pressure system to force the plastic into a bag shape, the mechanism to squash the parts together and no doubt there are a heap of other bits that make it all work, and then what happens when they need to make a design change? a new set of expensive molds, I do not pretend to know what is involved in this manufacturing process but it is more than just a set of molds involved and the maintenance involved.
They make it look simple but I would imagine there are a heap of hidden costs to make it look like that. The cost I quoted was just a guess and it would involve the main machinery as well, but some of the smaller plastic heating units can use over 100Kw of electricity just to heat up the plastic plus more to run the hydraulics in the machinery, I wouldn't like the electricity bill of the larger units compared to a welders electricity bill which would be negligible by comparison.
Ah ok i didnt think they would use that kind of power i thought along the line they may use steam to heat the mould
100kw is like a furnace i too wouldnt like that bill
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Good video of doing it the other way - roto molding. Once again, very equipment intensive. Would love to see these little cats here.
That looks awesome a very unique way of moulding a little unsure how they heat the moulds wasnt clear if its done while spinning on the rotiserie or in the white garagesOriginally Posted by scottar
There is a little bit of machinery involved mostly just moving the hdpe around the factory
A person could set that up pretty easy see how they just hand fill the moulds, heat than spin all done
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Roto moulding is how they make Polycraft boats and eskies and stuff, it takes longer than blow moulding but can be much thicker, the mould and material is heated to a liquid in the mould, then rotated around (roto) to cover the mould inside, the mould is quite complicated as the hull is hollow and is (usually) filled with some foam between the two layers.
Best post for some time good to watch
Could it be as easy as making the mould and rotiserie than running some type of induction heater cable around the mould
The cable heats up the mould amd melts the hdpe as the rotiserie turns, turn off the heat and a boats made
Would that work?
No im not planning on trying to make one LOL
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With rotational moulding, the mould and "rotisserie" frame are heated inside a big oven. Scary big. (I've seen one at a factory that used to mould canoes, water tanks and other big hollow products. Heating the mould directly would be far more complicated and expensive. You not only have to heat the mould, but also cool it at the end.
As I recall, the moulds for rotational moulding were much less expensive to make than for blow moulding or injection moulding.
All the moulding processes rely on millions of a set item to be made, or the price of making a few (like Polycraft boats) increases the finished items price, things like plastic fish boxes and so on are made by the thousands to keep the price down. There used to be a place near Newtown in Sydney (I think it was Nally brand) and you could buy stuff direct, I used to buy fish box "seconds" they had small flaws or colour discrepancies, but were cheap as chips.
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