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cnc machining

CNC Machining
Everything before this topic is preparation.  Machining is where the rubber meets the road.  All the steps of Computer Numerical Control before machining are just preparing for the machining phase of the project.One definition of machining is removing material with a tool.  You remove material in various ways to come up with the part or piece.

Machining can be performed on numerous types of material.  For example, wood, steel, aluminum, and stone.  Machining generally has higher tolerances associated with it.  When machining, you are trying to do something more precise.

In CNC Machining, we use some sort of tool.  This tool could be a grinder, drill bit, end mill, router bit or other tool.  There are infinite variations of tools.  Tooling generally costs a fair amount of money.  Once you invest in your tooling though, you can use it again and again until it wears out.   If you have a large variety of different tools, you will be able to perform a large variety of machining types.

Here is a list of common tooling:
Drill bits
End mills
Plasma cutter
Dovetail cutter
Fly cutter

If you would like to look at different types of tooling, go to one of these sources on the Internet:
Enco
Travers
McMasters-Carr
Grainger

Flip through a few of these suppliers’ catalogs and you will get an idea about the infinite styles of tooling.

CNC is used in the machining process.  Generally, you can get better accuracy, quicker production, and overall efficiencies when utilizing CNC machining.  This is why it has become so popular.  In the past, CNC machining was very costly.  Over time, it has become somewhat inexpensive and now people do it as a hobby.  I am guessing that is why you are here.

Here are a few different types of machines that perform various machining processes:
Milling machines
Wood routers
Plasma cutters
Foam cutters
Press Brake
Lathes
Cutoff saws

People have successfully applied CNC to virtually any type of motion control.  The only thing that will limit you is your imagination.

CNC Information Free Community Site:
If you would like to know more about CNC, head on over to http://www.cncinformation.com
Join for Free and you get 2 CNC ebooks. One is a GCode Quick Guide and the other is the CNC Info Site eBook. You also get access to the Free Video Series…Image to CNC Art when you join the community.

cnc machine

Machining Overview
When a controller converts signals from your computer into motion, your machine will begin to move.  You are now into the process of CNC Machining a Part. Machining generally is cutting or removing of material.  Most of the time we associate machining with metal, but you can also machine plastic or route wood.  Working with wood or plastic is basically the same as working with metal, but faster.

Machining
To actually machine something you need a few different things.  Since there are many things going on while CNC Machining you need to be aware of your safety.  This is where the safety glasses come out and the personal protective gear is put on.  Machining is a concert of movement, that requires many players. 

Here are a few of them:
Machine - this could be a milling machine, plasma cutter, wood router, lathe or drill press.

Spindle – Most machines have one.  This is the spinning portion of the machine.  Like of the chuck on a drill, a spindle on a mill or a 3-jaw chuck on a lathe.

Tooling – This is the tool that does the cutting or removing of material.  It could be an end mill, fly cutter, ball mill, etc.

Material – What you are going to be machining.  What your part will be made out of.  Steel, aluminum, wood, plastic, wax, etc.

Clamp or vice – imagine some material laying on a table and then you touch it with something spinning.  Your material will instantly go flying and possibly hit you.  This is why you always secure your material.  This could be with a vise, clamp, bolt it down, gravity, suction, etc.

Cutting fluid – Some machining processes don’t use cutting fluid.  Plasma cutters and wood routers don’t.  Cutting fluid or coolant generally shows up when you are machining metal.The fluid is used to cool and lubricate the process.

CNC – if you add CNC to the process you now have a computer, controller and cableing to worry about.  Keep these things out of the way or protected while machining.  Keep in mind a machine will be controlling another machine.  This is the cool part about CNC and also where you can get into trouble.

Different types of machining
I alluded to the different types of machining in the previous section.  There are different machining processes that are generally defined by what the machine does.

Here are a few examples:
Drilling – Drill presses, mills, hand drills, etc.
Tooling – Drill bit

Routing – Wood router, table router, edge router, etc
Tooling – Router bits

Milling – Mill, Bridgeport, 4- axis mill, 5-axis mill, vertical mill, horizontal mill, etc.
Tooling – End mills, ball mills, ballnose mills, fly cutters, etc

CNC Plasma cutting – CNC Plasma cutter
Tooling – Plasma torch

Cutting – Chop saw, hand saw, band saw, cold saw
Tooling – Circular blades, band type blades

Grinding – Surface grinder, grinder, Timesaver, belt grinder
Tooling – Grinding belts, grinding wheels

Turning – Metal lathe, wood lathe, mini lathe, bench top lathe, etc.
Tooling – Turning tools, parting tools, boring tools, drill bits

You can go on forever with types of machining and cnc machines.There are many types of unique cnc machines.  Anywhere you can save time or money by using a machine, people have found out how to do it.  Even if that means they need to rig it up themselves.

Different Sources of Tooling:
Enco
Travers
McMasters-Carr
Grainger

CNC Information Free Community Site:
If you would like to know more about CNC, head on over to http://www.cncinformation.com
You can join for Free and you get two free CNC ebooks. One is a G-Code Guide and the other one is the CNC Information Site eBook. You also get access to the Free Video Series…Image to CNC Art when you join the community.

cnc design

Tool Offset
I thought this would be a great place to do a quick talk on Tool Offset.  Tool Offset is the amount you must “Offset” the tool while machining.  For example, the tool paths that we created in Computer Aided Machining are located in the dead center of the tool unless you do something about it.  Most times you set the tool offset in your CAM program, but sometimes you might have to do it during the machining phase, depending on your machine.

What if you had a one-inch diameter tool, we will use an end mill in this example, and you needed to take off .25” around the perimeter of a 5” by 5” block of aluminum?  Without tool offset, the tool path would be around the perimeter of the block.  The end mill would take off half of its diameter or .5” inches.  You need to offset the tool so this does not happen.  In this case you would offset the tool outside of the block by .25”, then the end mill would take off .25” of material.

Zeroing the machine out
When beginning your machining, you always need to zero out the machine.  You need to let the control software know that this is going to be the starting point for the whole project.  When “Zeroing” out the machine, a lot of the time you will use an edge finder when milling.  Most times in Plasma Cutting, you will just pick your starting point on the steel and begin the program there.

The final “Part”
Parts are the outcome of your work.  That is unless you are making artistic pieces.  Parts need to be made to specification.  Most often machinists will check their parts as they come out of the CNC Machine they are running.  Many times, they will use a go/no-go gauge.  With a go/no-go gauge they can quickly check out the critical dimension of the part and reload the machine.

Chips?
Machinist call the material being removed “Chips.”  This is because most things that are machined are metal and they come off the part in chip form.Chips can be dangerous and sharp.  You have to be very aware of where they are flying as they are being removed.Many CNC machines will have enclosures to block these machining chips from flying around and hitting people.

CNC Information Free Community Site:
If you would like to know more about CNC, head on over to http://www.cncinformation.com
You can join for Free and you get two free CNC ebooks. One is a GCode Quick Guide and the other is the CNC Info Site eBook. You get access to the Video Series that is free…Graphic Image to Art when you join the cnc community.