Investment Casting or lost wax casting demonstrated

okay in investment casting or sometimes it's referred to as lost-wax casting unlike sand casting where you can use your model and your pattern over and over again for every loss wax or investment casting that's done that's model is lost in the form of the wax it's burn out and replace with the melted metal so as a results if you want multiple castings you have to have some way of generating multiple wax patterns so show you a little bit about how I go about making the molds and then we'll demonstrate injecting the wax into one of the most just to see the process of making the multiple wax patterns in front of us here to the left is a clay and what I've done is spread it out on the base of a just a piece of plexiglass and in front of it there is a little brass form piece I've refer to as a sprue former and I have a piece of wax attached to it and attached to the end of that wax is a Lincoln penny a u.s. one one cent piece the piece to the right was made from PVC pipe you can use PVC brass tubing aluminum tubing whatever but this is going to be the frame for your mold and typically I'll put a one and a half to two degree taper on the inside of this mold frame and I'll demonstrate in a minute the purpose for that but let me show you how I set this guy up before pouring the mold material I'm sorry the well the mold material in this case I use RTV what I do is take the the piece that I want to make the mole of in this case the penny and I'll press it down into the clay so it's attached pretty firmly and then taking the PVC pipe with the taper on it I will go around it and press it down into the clay and seal it so now what we have is we have our model inside the mold frame it's sealed and then we will mix up the RTV rubber and pour it into the mold frame to generate the the mold here's an example I'll open it up of a mole that was done for one of the parts on the Wilton vise this this setup was just very similar to what I demonstrated on the penny but here's the mole after the RVT material vulcanized is overnight you then take it out of the tapered frame and cut it with the exacto or razor knife and part it the best you can down the centerline and it's not that critical as long as you can get to two pieces to go back together the black piece in this case is a core and what will the reason for the taper is after you've injected or shot your wax into the mole when you open the mole up and remove your wax model you put it back in for another run this taper it goes down and you give it a slight tap and it locks it in and it makes it real tight fit with the two halves of the mole so when the wax is injected through the sprue opening from the wax injector it helps reduce any tendency for the mole to separate and open up which we'll call cost flashing the four years in the jewelry industry most of the moles were parallel sided molds and they were cut in cut in half and you would hold a couple of plates on each side of the mole and inject this into the wax injector well it's kind of awkward to try to keep even pressure on here and keep your wax pressure from opening up and causing a flashing so I've never used this I never have liked that method I prefer the tapered model of also over the years for bigger parts where it's not practical to have a tube I'll make the boxes and the boxes that I've made here have a taper there's a taper on the top and a taper on the bow bottom and when you the advantage of doing box like this you can pre establish your parting lines with clay and for one half of the rubber of the motive mature and get half of your pour and then you remove the clay and put them old reliefs on and pour the second part and you'll end up with a mole where the parting lines have already been established in your two-part mold and you don't have to worry about cutting now because once the top and one side is tapered when you take your model out and get ready to inject your wax it slips down there and you can just give it a little tap and it locks the mole in just like on this the tapered motion done with the cylinders it prevents flashing it's a very effective way to to make larger moles okay what we have here is my small wax injection pot the temperature controller which keeps it regulated for the proper temperature for the wax that you're using and in front of the temperature controller there are three moles now there's three moles for parts for the little Wilton vise which is over here on the side and what I want to do is is just let the camera run I'm going to kind of stand aside and I'm most sequence through all three of these moles by injecting them and what I'll do first is inject the three moles and then by the time I get the third mol injected I'll come back to the first mole and open it up and remove the wax injection the wax that's in the injection pot starts out as flakes just little pellets of law and then they melt in this particular injection pot is a hand-operated it's got a little hand pump in it I'll zoom in here where you get a closer view of the wax coming out of the nozzle okay so I've raised a lever on the pump and come down you should sit you should be able to see the wax escaping from the the sprue opening here so I will start off with this the small mole here raise it up it just real gently push down and when the mole fills you will feel back pressure on the mole so you at that point you stop pressure you stop pushing and just hold it for a few seconds and give the wax a little time to cool okay the part of leaving the pressure on the mole after you fill it fill it has filled is real critical because it keeps the wax from sucking in and it keeps pressure while it's cooling to give you a better cleaner mole so what we'll do now is open up to three that we that we shot this particular piece here is the end cap for the Wilton vise there's a core inside of this mold to form the the hole and I'll remove the core and there's our part so by placing the core back in the bowl putting the mold back together drop it in the in the tapered mo giving us that little little tap we're ready to shoot another way so it's just it's best when you're shooting the most a house multiple moles set up so you can sequence through this was the second one that we injected it's the front jaw it also has a has a core in it and we just do a slight twist and pull the core out and there's just another wax model same procedure put your core back in the mold drop the mold back into the mold frame Oh okay I put the core in backwards it's always harder to do something when you're trying to film it okay let's try that now you got another one the last one that was shot on the first go-around was the base for the the Wilton Vice the big black Corbin I think it's a piece of Delrin that helps form the opening in the in the base so what we'll do is we'll put we'll try to group them and put one of each wax that we just shot at a grouping along with the body okay here's a group shot of the three modes that we just injected with a sample of the wax it we took out of the mold sitting on top of each model and a little ice in front of it at this point what we're going to do is take these things and attach them to a tree and they'll go inside of a flash that will be filled with investment so what I'm going to do is get set up to show you how I attached these multiple waxes to a tree for doing multiple castings of the parts so we'll be back in a minute okay in the background you see the flash size that we'll be using I think it's a two and a half inch diameter by four inches tall and in front of it the rubber base that just flash will be pushed down into and seal the flash so when you pour it it must but it won't leak out the bottom the flash will be wrapped with masking tape until investment sets something that it will be removed for the burnout process our objective here is to try to get as many parts as we can on that red spruce that's attached to the sprue base there's a rubber sprue base and to the right you see a casting I did yesterday and it is loaded with many small parts so what we try to do is be as effective as we can because the investments expensive the whole process is time-consuming so what we try to do is get as many parts out here as we can now a little point here most all of the sprue bases that's commercially available are very similar to the one you see here they fit the diameter of your of your Flash size that you're using well sometimes the geometry of the part that you want to use is not compatible with the size and what I mean by that if I wanted to attach several of these little vices to this sprue the problem is it's too big and it will push the part too close to the side of the or not at all so you know yes typically your option is to go to a larger flash well you go to larger flash it's increases everything the cost of investment your burnout time etc so what I came up with is I take these rubber sprue bases traditional like this where the sprue is in the center and I take it cut it out get rid of it and then on the lay I turned down a tapered screw base and now I can offset this from the center of the base and I just barely attached it with some tacky wax and seal it with wax at the bottom and put my sprue on the top of the white sprue base there and now with in this configuration it gives me a lot more capacity within a small sized blast so now I can go in and mount multiples away in a different angle and I'm not restricted by the distance that I had to live with when the spruik was in the center so just just a little idea I came up with it's I use it quite often now let me let me show you what we've got on the table here for attaching these waxes to the sprue base off to the right here the outlet box there's the rheostat in there I think it came off of a fan dimmer or like a light dimmer so there's risk that in that it controls two outlets these two outlets I have low wattage 30 35 watt solder dyes and I can regulate the setting on this wrist out to get the temperature of the solder a guy just where I want it for melting and working with the wax off to the right up so off to the left here is this sub sampling of the different types of waxes that that I use and most everybody in this business uses the red stick to the right is referred to as sprue wax that's what's sticking up in into the sprue that able to attach my multiple parts to the little skinny yellow piece is just a smaller sized sprue wax and it comes in it goes all the way down in size to go into the thousands the yet light yellow wax to the to the left moving down the line this is referred to is tacky or sticky wax and that's exactly what it is and what I've done is taken a couple of sticks of this and melted it into the little lid that's in front of it and when you first attach a piece to your sprue just a slight little dab of that will let you tack it in place until it'll hold until you can seal it around to make sure you've got a good good seal joint all the way around the sprue the brown stick flat stick is referred to as sculptors wax and this is you could take it and knead it and work it with your fingers and it work it around and sculpt and the more you work it and knead it together he gets more pliable this is typically what sculptors used for making their their sculptors prior to a heaven of cast and what I've used this for quite successfully is doing n lay work and what I mean by that if I want to in lay some metal in the wood or ivory or whatever I will work work out the cavity in the wood the ivory and typically either using a pantograph or the CNC i will route it out and put a cavity into the material you take the sculptors wax and press it down inside of the cavity and then when it gets pressed into the cavity you just leave a slight skin connecting in this case here so that all the letters will connect and you rub it with ice it harden it and once it gets good and hard with light air pressure you could blow it out and then this can be screwed up and cast and when you cast it it will drop right back into the cavity that you blew it out of you leave the skin a little Prowse or what you put it down into cavity you can file it and send it down and it blend it into with the material the the next wax here the purple stuff is referred to as a purple buildup I think of what it's called but it's specially formulated so if you've got a pattern of wax pattern that's got a little void in it or defect it didn't quite get filled when you injected it the characteristics of this wax it melts at a lot lower temperature than your injection wax and it flows really smooth so you put a little loan into the side or down and you touch it and it will blend in and fill any voids usually it's best once you get the void filled just leave it alone wait till it's cast that it worked it down with files versus trying to clean up in the wax environment so what what I'm going to do here is I'm going to try to get the camera set up and zoomed in on my my sprue base and I'll work from and I'll start attaching some parts to the sprue I have already sized the length of the main sprue such that when it's attached to the base in the flash to fit down around the sprue brace prior to pouring the investment in the flashed thus proof is of the right length you have to be careful and not to get to sprue too long so that it comes too close to the top of the flask in this case here I've allowed for about all the lower half inch clearance between the top of the sprue and what's going to be the top of the investment wants to flash this port if that distance is not maintained there won't be enough investment in the top of the flash that when you put it in a vacuum unit sometimes the vacuum will pull it and break it loose in disaster happens so this little articulating base here enables me to position the the part or the sprue so that I can get to it rotate it twist it and what I will do in each one of these cases is take to the sticky wax here real tacky and just put a little drop of it onto the runner there and see it's always you always have to figure out the best way to orient these things I think this is going to so what I'll do is just melt the load a little detent in here and I still got my sticky wax on there and I'll tack it in place and once this in place you can go around and seal using the sticky wax and make sure there's no gaps and in this case here I want to lower it just a little bit so while while the wax is still tacky and bring it down a little lower angle so that I'm not getting too close out to the edge that looks good there so I've got quite a few of these to do I'll just repeat to repeat the process as I go around apply the sticky wax a little beat jump there and you try to group these lay them out to the best you can to get maximum utilization you know of the space inside the flask what I'm going to do at this point is go ahead my goal is is to try to get all these waxes that you see on the sheet of paper towel here try to get all of these mounted onto this sprue and it'll be quite tight once I get there again here's an example of one I did the other day that's already been cast so we'll load it up with as many parts as we can get on there and I'll come back and we'll do a shot of it once I get it it load it up and you'll see what it's going to look like before we pour the investment over the wax models we've got all the parts attached to the main sprue and we managed to get them all on there as you can see it's fairly crowded they've also wrapped masking tape around the flask and at this point what we're ready to do is slip the flash down over the base and you know surround the parts and then we'll we'll go mix up some investment and pour the investment into the flash so that it will surround all of the waxes so that wraps up the the piece about attaching the parts to the mains fruit okay let's go for some investment fill it up okay we're getting ready to mix up the investment in form in the flash just an overview of the process one of the things you really have to pay attention to is accurate measurements on the weight of your investment versus the amount of water it's very critical and every manufacturer of investment will provide you with a chart to follow and it's very critical that you maintain the exact weight and water ratios when mixing you put the water in the bowl and always add and pour the investment to the water I've already pre-measured I have two pounds of investment sitting on the scale and in the black rubber mixing bowl that's sitting on top of the vacuum unit I've measured out the appropriate amount of water for two pounds of investment this should give us enough investment to pour and fill up two flats when the investment in water mix that's the start of your cycle and you have exactly nine minutes to to finish if you exceed two nine minute limit your investments going to start setting up and getting hard so we've got to do all this in nine minutes we first mix the investment in the bowl D gas it and then pour it into the flash and then D gas the flash and at that time when you set to flash down they should remain undisturbed until the investment sets so we've got to do it all in nine minutes so there's plenty of time but you just you don't have time to stop bachelor to telephone so with that said we'll we'll start the pour and I'm going to focus in here a little bit closer so maybe you can get a better better view so there's your two pounds of investment we've already got the water in the mixing bowl we're going to add the investment to the water tip where I'll hand start initially to get to water and the investment premix before I hit it with the electric stir [Music] I'm not sure if you can see the vacuum gauge on the vacuum unit but it's going to come up to 0.6 27 inches full vacuum the investment in the front of the bell jar will start rising and once it gets past 26 degrees and gets pretty much all the air out of investment it will then collapse and fall down in the mixing jar okay it just peaked out and it just it just fell so at that point we pretty much got all the air out investment turn the vacuum off grab a couple of Flast here I like to pour the investment down the side of the flask not directly on to the waxes because they are fairly fragile okay we're going to Reeve acumen and there's a vacuum in it this time I will be jogging the plate on here to help get the investment mixed around and hopefully and I ever track and Travis inside of the boxes [Music] now once once you've done the final vacuuming set to flashed aside and do not disturb them until investment gets completely hard okay that wraps up the investment pouring process we have six lasts and we'll leave these set for a couple hours until they cure a little bit more and then we'll put them in the high-temperature oven and take them through the prescribed burn out cycle depending on the size of your flashed you either have a anywhere from a six eight or twelve hour cycle obviously the larger your flash you have to bake them and take them through a longer cycle the size of these flash will take them through an eight hour cycle starting out at 300 degrees going up to 700 then a thousand and then we'll hold it at 1,350 degrees for about three and a half hours and then ramp it back down to the casting temperature that we want to flash to be at and in our case we're going to be casting these in aluminum bronze and the recommended flash temperature for aluminum bronze is 1,100 degrees so we'll ramp it down from 1350 to 1,100 degrees let it stabilize for an hour hour half so that to flash throughout its 1,100 degrees and at that point we will take them out of the oven one at a time and put them in the vacuum unit and pour the molten metal and hope we get some decent castings out of it so you when we start the the casting process [Music] okay what what we're going to do here is attempt to do a live filming of a live investment casting demonstration we're looking at the burnout oven right now in their six stainless steel flashed in the oven that have been in here or in the oven for about eight hours going through a regimented burnout cycle the flash have completely burned out all of the wax that was inside of the investment is no longer it's completely gone the flash temperature is roughly 1100 degrees and we're going to go through and pour a few of these and hopefully film them as we're going through the operation what I'm going to do real quick is open the oven door so you can see the flash that are inside the oven awaiting to be investment cast report okay that's a good shot so what I'm going to do next is reposition the camera and show you the two pieces of equipment that we'll be using for the investment casting okay the unit on the right is an electric furnace that currently is at 2075 degrees and it contains about a pound and a half of molded aluminum bronze alloy that we're going to be pouring the unit to the right is a vacuum unit the when I begin the casting process I will take the flask out of the oven and walk over to the vacuum unit with the hot flash and drop it down into the vacuum chamber there's a flash sitting on top of the char you nut right now but it's empty there's nothing in it just to show you the size of the flash that we will be casting so once I dropped the flash down into the vacuum chamber I will turn the machine on and watch the vacuum gauge to insure that I have a good seal of the flash and once I verify that I will take the graphite crucible out of the electric furnace and pour the molten metal into the investment flash it soon as it pours and it's full I will put the crucible back in the electric furnace to show it continue to stay hot and I will let the poured flash set on the vacuum unit for just a little bit until it the hot button solidifies enough that I can safely take it out of the vacuum chamber and set it over on the bricks to the left at that point if all goes well I will continue to work and by going and taking another flashed out of the oven and repeating the process if all goes well I'll just leave the camera running I have enough molten metal in the furnace to pour three three flasks and we might have to pause you know at one point to let the metal get back up to temperature because when you pour it and put the crucible back in it cools down with that said because there's so much going on it's so quick as you're doing this process probably it will be a solid pour unless I can manage a word in here there but typically it's just a video mill visual recording at this point on okay here we go [Music] [Music] okay you see the button is pretty well solidified it's going to stay cheery rent for a few more minutes at this point I'm going back to camera back to original position and grab a couple more flash stand and pour those at this time you [Music] [Music] [Music] [Music] okay well up let that one cool down for just a bit before we remove it and set it on the bricks at this point I'm going to pick up the first flash that we cast the button and the metal has appeared to cool enough so we're going to dunk it and quench it and see what the casting looks like let me try to focus in here on the barrel okay so we're going to duck it in here the water is going to react with the hot investment hopefully we'll have a set of castings fall out in our hand here shortly [Music] okay it looks like a keeper we got eight barrels for the 1911 and eight hammers we'll get some close-up shots of these later maybe while I'm going to position a camera for the next pour before I do that I'm going to remove the flashes in the unit the vacuum unit [Music] ha okay guys as I said earlier this is a live demonstration so it was anything live things go wrong now one of the rules and investment casting when you put your parts inside the flash you have to maintain a minimum separation between the top of the flash and the top of your your waxes what happened I exceeded that and I did not get away with it when I place this flashed in the vacuum chamber and turned on the vacuum I heard a pop and I knew something was wrong what happened is my parts had been placed too close to the top of the flash and there was not enough investment in the flash to withstand the vacuum pressure and what happened is the vacuum pulled out and separated some of the investment and broke away and obviously at that point had I poured demoted metal it would have gone straight through into the vacuum chamber and I recognized what had happened so I turned it off and remove this this flash so so far we've put tried to pour three I'm sorry for flash we've had what appears to be three successful pours this was the first one that I've done into the into the water in the casting came out don't want to pick it up it's about 900 degrees now a little trivial information let me zoom in over here to the vacuum chamber you see the white ring that is a silicon pad and generally when you're casting metals like gold and silver and lower melting temperature alloys your hot flash can be placed directly and sealed on this silicon pad you can see some of the burn marks the silicon pad does where you know I don't know what the life I miss but you do have to replace them occasionally well because when I'm casting aluminum bronze it has a lot higher pore temperature and flash temperature my flash temperature has to be 1,100 degrees well 1100 degrees in these stainless steel flats would pretty much burn up just silicon because it's only good for about a thousand degrees so what I did is I made these little rings out of aluminum and I cut out a recess in a dado and I lined it stuffed it with that bestest it's a old stock asbestos that was used in the early days for sealing cast iron plumbing pipes and the asbestos obviously will withstand quite a bit more temperature and I've used this particular ass bestest ring for this this ring here I'll probably 4-500 cast and it still it's still healthy 1,100 degrees to asbestos is just you know lukewarm so with that said we're going to cut the camera off here a minute and get ready for the last pour [Music] got a whole bunch of little small 1911 internal parts on this particular flashed here just a few more minutes we're going to take the last flashed and ducked yet and see what it looks like okay let's try flash number three it's cooled down enough [Music] looks very good looks very good a bunch of much more of 1911 internal parts these are the barrels and some of the internal parts there's a total of 49 castings I'm sorry 29 castings there's a total of 29 castings that go into this little miniature 1911 that I'm mass producing and I was hoping that let this be the last session but obviously with the one flash that we lost I might be a little short for the total number of 25 but I know I've got enough for at least 15 and start with that'll keep me busy for a couple hours okay this unit I'm focused in on now that's setting up on top of the vacuum casting machine is an antique cast-iron ingot mold and what I want to do at the end of this last pour I've still got that will still be molten metal remaining in the graphite crucible so after I pour the flask I will set the the mold will be sitting down on the asbestos pad of the table and I will pour it with the residue metal that's left in the in the electric furnace and when it cools I'll have an ingot that can easily be banned salt it can be recast in the future so after I pour the flash watch the operation where I pour and fill in get mold with the leftover molten metal [Music] [Music] [Music] okay here's a close-up of the last flash I just poured to the left is an ingot mold it just about filled but you can see a little bit of the solidified bronze at the top of the mold we'll open it up after the coos later on okay I thought I'd get a close-up of the flash that the bottom got sucked out Ivan busted this is setting up if you look real close down the center hole was the main sprue that all the wax components were attached to and what you see is little channels coming in that's where the the watches were attached to that Center sprue and as you pour the molten metal in from the from the bottom of the flask the atmospheric pressure because the flash is under vacuum forces and pushes the molten metal into these little cavities that radiate off of the center sprue it's not vacuum that's actually pulling the metal in it's the atmospheric pressure it's similar to sucking on a straw on a soft drink and creating a pressure differential and then the atmospheric pressure is what's pushing down on the liquid in the cup and forcing it up into the straw the same process I'm gonna turn this flashed upside down where you can get a closer view of what the button looks like I guess that's about a 1 inch diameter cavity and that's your your aim point when you're pouring the molten metal and you know you don't have much of a target but it's enough we're going to take a shot of the last flash we poured looking at the color of the button it appears that it's about ready to dunk so what I'm going to do is leave the camera set up on a close view of this bucket and I'll remove this one and maybe you can get a bird's eye view of watching the the investment dissipate when it hits the water [Music] okay that looks like another keeper I've got a barrel and it's a trigger bow and in miscellaneous 1911 parts initial looking at me they look like you're all good the rest of this investment can be hit with a high pressure garden hose and just wash right off of there it comes off fairly easy okay what you see here setting up on top of the vacuum unit is yesterday I cast the Thor assemblies on the left two of them are Wilton vices the big vices and the small vices at this there's three complete vices in each grouping and then the other two to the left or vice grips I think it's a half a dozen pair of vise grips and then the four flashed on the right or what we just got through casting a video and today and we can't we can't leave this video without taking one last goodbye and look at the failure so there's one that didn't work the investment casting process is it's very similar to baking a cake if you follow the directions and don't fudge and don't cheat it's it's pretty predictable but it's not unusual to not have a perfect session let's see if we can open this up mister bullet mo our bullet mold this ingot hole and there's our ingot that we we made and this can be easily been solidus it's about a quarter of an inch thick and then we can Manso it and put it back in and remelt it on our next casting session so with that I'm going to wrap it up and just I took the castings outside and hit them with a garden hose and washed off and hosed off most of the investment you see the four castings that we did today and a little 1911 in the center let me zoom in here on a array of the parts these are pretty much been washed free of the investment there's the barrels okay miscellaneous hammer struts and fine pins and extractors tell a little bit more about the parts now that you've been washed off okay we're going to wrap it up with that the last step in the investment casting process is to remove the castings from your tree and probably one of the most critical parts you really have to be careful detaching your castings I use two methods set up in a fun office on the bench here we've got a dremel - a motorized - and also a jewel or saw with a real fine jeweler saw blade in it there's no secrets it's just be careful and cut them off being careful to cut them as close to the main sprues you can and not get into the any working part of the casting if there was a magic secret that I could pass on to you it would be this right here this tube of white lubricant referred to as Beaulieu it's a Boeing developed lubricant developed by Boeing aircraft on the west coast and it is absolutely a fantastic lubricant to put onto bandsaw blades jeweler saw blades and what I found it to be most effective is getting most effective is loading up and putting a lubricant on to the cut off wheels and what it will do it will put a light film of lubricant on the cut off wheel and it will prevent them from overheating which is what costs these wheels to wear it down in the first place and typically lead to wear and breakage but if you periodically don't let the the cutoff wheel get hot just keep applying the bow Lube - it periodically to keep it cool you'll find the life of your cut-off wheels will be tenfold same thing on your bandsaw blades or your jeweler saw blades just load it up a little bit and it will it will make it cut quicker faster and make your blades last longer and stay sharp and longer so that's my testimonial for mow Lube I'm going to set down it to cheer here cut a few off you'll get the you'll get to drift on it and then we'll wrap it up [Music] [Music] [Music] [Music] [Music] II [Music] okay well you you've got a little room to get the the cut off way off into the area that you want to cut off that's fine but on some of these is packed in pretty tight and you don't have room to manipulate and get it to without interfering with another one the jello saw blade sometimes is your best ooh that one land it on the coat okay with that it's just kind of like Egon elephants you do it one bite at a time until they're all off and I wish there was a faster way but that's my story and I'm sticking to it okay I hope you enjoyed the video and possibly picked up a few tips for future projects and thanks for watching and don't forget to subscribe for future videos have a nice day

Channel: Paul Hamler

Views: 116,960

Rating: 4.8130617 out of 5

Keywords: CyberLink, PowerDirector15

Id: 06t2_2I2tZk

Length: 65min 20sec (3920 seconds)

Published: Wed Apr 26 2017