Metal Casting

Casting can be defined as a process of manufacturing, which implies pouring of a ‘liquid’ material into ‘A Mold’ containing a desired shaped hollow cavity, and then made to solidify. What needs to be done to finally complete the process is to take out the casting and break it apart so you can see your finished project. The use of casting is ‘forming hot liquid metals’ or numerous metals that are cooled after having the components like clay, plaster, concrete, and epoxies mixed. A lot of times, you will find complex shapes being casted because casting allows you to do this. Casting came into being around 6000 years ago. ‘Copper Frog’ is the most ancient casting existing till date since 3200 BC. The process of casting has two distinct subdivisions: non-expendable and expendable mold casting.

‘Non-expendable’ mold casting: This technique is inclusive of at least 4 distinct methods: continuous, centrifugal, die, and permanent casting.

Continuous casting: Continuous DIY Casting can be defined as a refined process of casting for high-volume, continuous production of ‘metal sections’ with constant cross-section. The pouring of molten metal into a water-cooled, open-ended copper mold takes place. This allows a ‘layer’ of ‘solid metal’ to be formed above the ‘still-liquid’ center. Continuous casting is widely accepted due to its cost-effectiveness. The metals continuously cast are aluminum, copper, and steel.

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cnc tutorials

G-Code is the common name for the programming language of CNC Machines.Somewhat of a general, catchall term for CNC programming language.  Very few machines adhere to this standard today.  There are as many varations as there are manufacturers.

This is how I think of G-Code.  It is a simple language built off of the Cartesian Coordinate System for motion control.  That is a mouthful.  I don’t know if that is exactly right, but you will get my meaning in a second when we go through some code line by line.  You will remember your High School Geometry soon enough.  For the real pros out there, you know there is much more to G-Code then that, but it is a good place to start thinking about it.

You will see many variations of the G-Code name like:
Gcode
gcode
G-Code
g-code
G Code
G-Code

Are there other “Codes?”
In a word…Yes.We will get to that information in just a minute.  G-code is also the name of any command in a CNC program that begins with the letter G.  G-Codes generally tell the machine to perform an action.  G-Codes can tell machines to move a certain distance in the X-Axis for example.  Or, make a rapid move to another location.  Or, move in an arcing fashion while milling.  An on and on and on.

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cnc programming

One day I knew I had a problem.  I just spent 4 hours with my plasma cutter in my right hand.  I had been cutting out patterns I had traced onto a sheet of metal.These interesting shapes were going to become my coffee table.  Everyone complained to me that I didn’t have a coffee table.  I thought, “I’ll show them” and began to build one.
Why make a coffee table out of metal you ask?  The quick answer is that I wasn’t much of a woodworker at the time.  On the other hand, I used to weld professionally and knew I could make anything out of metal.  That is how it all began, making a coffee table out of metal.

Now if you knew me, you know that I can’t just make something normal.  My brain is the scheming type that has to do things differently then the norm.  I wanted to make a table that would knock people’s socks off.  I thought a funky looking table, made out of metal, with casters and lights would do the trick.  You know what?  It did. 
I really had a ball making this table.  I mean I had serious fun.  So much so that I started to design others.  I began showing photos of my work to everyone I knew.  On top of that, I was getting good feedback.I just came across a new hobby, it was furniture making.  Who would have ever thought I would pick up furniture making as a hobby.

While making this first table a problem arose.  It is the one I mentioned above with my right hand.After cutting out all those parts my wrist really began to hurt.  While welding professionally there was always the threat of Carpal Tunnel Syndrome.Human welders are continually afflicted by this injury and others because of repetitive motion tasks.
If you repeat something over and over and over and over, your body gives out at some point.  After cutting up these table parts, I knew I couldn’t go on doing this for a hobby.  I knew something would have to change or the new hobby would break my body.

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learn cnc

In a word, no.  You will probably need to know how to quickly scan your G-Code if you are having problems during your machining simulation.  Other then that G-Code and a CNC program are throwaway programs for the most part.  What do I mean by that?  Let me explain.

Let’s look at a specific design.  Let’s say a 12” by 12” square.  You build your model, run it through your CAM Software and create a CNC Program made up of G-Code instructions to your machine.  Say tomorrow the job requirements change to a 24” by 24” square.  Do you go into your G-Code line by line and change the code?  Most people wouldn’t.  They would go back into their CAD or CAM program and scale the square up to 24” by 24”.Then postprocess the job to get their new CNC Program.

There are some people that would do this editing line by line because the design is simple.  Now think of a complex shape and what scaling it up or down would entail.This would include changes to the G-Code and reviewing it line by line.  We are talking thousands of lines here vs. going back and quickly scaling the model and spitting out some new G-Code.  And that is why G-Code is throwaway.  Use it over and over when you can, but don’t fret over archiving it if something changes.  It is much better to make a copy of the design (CAD File) in its original state and save that somewhere.  That is much more useful.

Post Processing??? - Now you have me worried.  With all the variations in G-Codes and M-Codes, how will I ever keep it straight?

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Metal Casting

Green Sand: Green sand is also called as foundry sand or molding sand. This is utilized for sand Metal Casting . When this sand is oiled or moistened, it has a tendency to pack well and retain the shape. Green Sand is made up of three things: Pulverized Coal, Water, and Bentonite Clay and Sand. Out of these four components, the biggest part is that of the sand.  There are several proportions of these four components. The different ratios are used to adjust the surface finish, moldability and capacity of the hot molten metal to degas. The prime use of this sand is in the Casting . The coal is usually called as sea coal in foundries. The Amount of Sea Coal is just about less than five percent. It undergoes partial combustion when there is molten metal present and this causes offgassing of organic vapors.

Green sand is stored in flasks (as the casters call the container). Boxes without the bottoms or lids are these types of boxes. This box is divided into two half parts and these are connected together. These halves are called as the top or cope and bottom or drag flask.

As per its name, green sand is not green in color. The word “green” is used as it is used in the wet state.

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prototyping

Since Rapid Prototype came into being, many businesses provided with the service of prototype development. Earlier, such companies were known as service bureaus and they allowed the users to access the unproven and expensive technology. In the early period of rapid prototyping, these service bureaus provided with advantages of Prototyping development minus the soaring upfront expenses and major risks of applying a new technology that was relatively unverified and hovering on the brink of rapid obsolescence. In the beginning, the service bureaus provided file conversions for narrowing the operational gap amidst 2D data and 3D CAD models. Due to this, the large companies that had not yet transitioned to solid modeling were benefited greatly.  

As the technology of rapid prototyping progressed, most of the service bureaus have undergone role modifications and they promise to deliver greater advantages beyond initial expense reduction and ownership risk. There are several companies worldwide offering the rapid prototyping services.

Advantages of Rapid Prototype Services: The advantages of rapid prototyping services are by far many. The rapid prototyping services provide advanced rapid prototyping technologies. The product development phase is what you want to get faster at so that you can get the product to market faster and have a competitive edge. The rapid prototyping services allow the users and producers to achieve the designing and prototyping goals. The innovative product idea can be successfully realized into actual product of high quality with the help of rapid prototyping services. The rapid prototyping services deliver the finished product beginning from the product idea, conceptualization and prototype development. You can save money and time as well, as rapid prototyping allows the production on low volume basis directly from the designing data.

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Prototype Development

In the Rapid Prototyping available in the market these days, generation of output takes place from programs of mapping which support 3D modelling programs or 3D CAD programs. Some companies have their own soft wares for PLY, VRML, and STK formats to allow 3D viewing, scaling and labeling of text, and fine-tuning preceding printing.

Working: All the 3D Printing posses five basic process functions for creating a three-dimensional model.

First - The Print Surface is fed with a unique powder.

Second - The powder is spread on print surface by a roller at a preset depth. This process takes just a few seconds for its completion.

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Metal Casting

A casting pattern is basically a shaped form of either metal or wood where sand is packed around it in the mold. When this pattern is removed, the resulting cavity would be exactly the shape of the pattern object that was to be cast. The casting pattern should however be designed in order to be easily removed without any damage done to the mold. The pattern should be also be perfectly dimensioned and should be very durable for the intended use. The patterns that are used in sand casting can be made of plastic, metal, wood or any other material. The casting patterns are made to the right standards of construction this is basically because they can last for a reasonable time. The long term of the durability of the pattern really depends on the quality grade in the casting pattern. If the pattern is made of right quality then they would be constantly providing dimensionally perfect casting patterns.

The process: The process of making Metal Casting is actually called as pattern making which is in fact a skilled trade which is related to the trades of die and tool making and mold making. However this also sometimes incorporates the elements of fine wood making. The makers of casting patterns basically learn their pattern making skills through trade schools and apprenticeships over a number of years of experience. There is also an engineer who a few times helps in making the casting patterns but in fact it is the pattern maker who carries out the design.

Design: The Metal Casting incorporate proper allowances for the shrinkage and this process is called as contraction allowance. Their accurate values however depend on the alloys that are being used and the accurate sand casting methods that is used. There are a few alloys that have the overall linear shrinkage of nearly 2.5 percent as other alloys might actually experience 0 percent shrinkage or even a light positive shrinkage or it might also increase the size in the casting process. The amount of the shrinkage is also dependant on the sand casting process that is employed for instance chemical bonded sands, clay bonded sands or other bonding materials.

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DXF Files

What I used to do…
Before I found design software I was in the stone ages.  I would actually hand lay out a template on a piece of paper.  Then cut it out.  Next, I would tape the design onto a piece of steel and trace around it with a Sharpe Marker.  Finally, I would cut out the piece I wanted.

No matter what, it was never exact.  There would always be something wrong.  Things like wavy lines, gouges and “unique parts” were the norm.  Measurements were never as exact as I would have liked either.  That usually caused some fit-up issues, followed by some grinding.  If you know anything about fabrication, grinding is the enemy of your time.

Why use CNC art design software?
I knew there had to be a better way so I found some design software to try out.  Yes, it does take some time to learn.  Think about it, like anything else in life, something that is worth it takes some time.  This is also the situation of taking one step backwards to move ten steps forward.

Advantages of using CNC design software:
Saved file you can use over and over
Transfer the design to others
Can use exact measurements
Repeatability in design

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CNC Control Video

The CNC Controller generally resides in the shop somewhere near the CNC machine it is controlling.CNC computers don’t have to be the greatest, every Bell and whistle type of computer.These are the powerhouses.  Save your money for a good design computer.  You will save much more time having a fast computer for your designing.

A control computer doesn’t have to be that powerful for a few good reasons.  It doesn’t have the workload.The control computer takes G-Code and turns it into signals that transmit to the machine controller.  Turning G-Code into signals is not that labor intensive for a computer.

I have used multiple types of control computers.  Everything from a 486 DOS running “$30 special” to a modern Dell with Windows XP.  I have yet to try one with Vista.  I will keep you posted.  Generally I like to find a good used computer for a couple hundred bucks, wipe the hard drive and only load the control software onto the machine.  That way you know what you have.

There is another good reason you don’t want to spend a lot of money here.This computer will be located in the shop.  Dirt will be located in your shop.  Using logic here, dirt will be located in your computer.  If the computer does go belly up, you aren’t out your children’s college tuition.

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