Archive for October, 2007

CNC stands for Computer numerical control. Just about every business that operates a manufacturing machine will usually have a cnc programming service operating it. The basic function of a cnc programming service has a cnc machine running it. The cnc machine is an automatic, precise, and consistent motion control mechanism. In the past, most automated machines needed someone to stand by the machine to make sure it was lined up properly and made sure that it repeated a certain function that is required from the machine. For a better explanation, I’m going to use the example the website I researched for this information used to make things a bit more clear. A drill press is used to machine holes, this is a repetitive motion, however, a person must stand over the machine to line up the drill with the holes and make sure the drill stays lined up. A person is required to do something every step of the way. However, a person can only do so much, and as production grows so will the amount of ?holes? so to speak, and the operator will eventually find it hard to keep up. In order to create more production, a cnc programming service and set up can be added. The cnc machine can do everything that an operator would be required to do. Once the machine is setup and running, it can take the place of the operators, the cnc machine is so easy to run, the operators tend to get bored during lengthy productions.

The cnc machine or course can do much more complicated operations that require much higher skill levels. A cnc programming service can improve automation so much that most of the time operator intervention can be reduced or all together eliminated to do other things. The second benefit is that cnc programming services and technology is consistent and accurate and once the program is verified, the machine will run efficiently and consistent, no matter how many work pieces need to be produced. A third benefit offered by most forms of CNC machine tools is flexibility. Since these machines are run from programs, running a different work piece is almost as easy as loading a different program. Once a program has been verified and executed for one production run, it can be easily recalled the next time the work piece is to be run. This leads to yet another benefit, a fast change over. Since these machines are very easy to setup and run, and since programs can be easily loaded, they allow very short setup time. Rather than applying completely mechanical devices to cause motion as is required on most conventional machine tools, CNC machines allow motion control in a revolutionary manner. All forms of CNC equipment have two or more directions of motion, called axes. These axes can be precisely and automatically positioned along their lengths of travel. If you need more information about cnc programming services there is a lot of information about it online.

About the Author: Leeanna is an expert author who writes for CNC Programming Service

Here is a cool story I came across that has everything to do with CNC and Halloween.  Here is a unique use of the technology.

World’s fastest Pumpkin carving: Halloween pumpkin carving tradition slashed to 30 seconds flat

FRASER, MICHIGAN   October 28, 2007

(PRLEAP.COM) Halloween is this week. Have you carved the pumpkins yet? A company in Fraser, Michigan has come up with a novel way to quickly make pumpkins into jack-o-lanterns. By using CNC waterjets they have turned the tradition of spending hours carving pumpkins into an activity that takes a fraction of a minute. Yes, it is a bit ridiculous but the pumpkins look really cool.

“Actually, my kids came up with the idea.” said Tom Monroe, Jr., of FluidCut, a waterjet cutting service, “They always see the amazing things we cut with the waterjet so they asked me to use it for their pumpkins. We cut everything from cutting glass sculptures for artists to armor for military tanks. Cutting pumpkins isn’t a problem.”

Using a water to cut food is nothing new. Much of the packaged food you find in the grocery store is cut with ultra high-pressure waterjets. However, carving the pumpkins with the waterjet does have its difficulties. The water is so powerful it cuts through both sides of the pumpkin. There are tricks that FluidCut uses to alleviate that problem.

Waterjets use ultra-high pressure water to cut almost any material. When cutting hard materials like copper, glass, or granite tile, an abrasive is added to the water. The most commonly used abrasive is the mineral garnet. Monroe said for pumpkin carving only water is needed.

Carving the pumpkins with the waterjet allows FluidCut to cut designs that are not possible with a knife. The kids’ favorite is the Homer Simpson jack-o-lantern, because the eyes and tongue are cut in a continuous spiral so it looks like they are popping out of Homer’s head. Adults seem to like the pumpkins with portraits of classic Hollywood stars like Marilyn Monroe and James Dean cut into them. You can see more pictures of the extreme pumpkin carving at the Halloween link at www.FluidCut.com.

The machine can carve pumpkins in seconds, but Monroe said he has to get back to work cutting other things like marble floor inlays and aluminum machine parts for his customers. Carving pumpkins with the waterjet does make some amazing jack-o-lanterns for Halloween but Monroe added he still is going to take an hour or two to carve some pumpkins at the kitchen table. “No matter how fast I can cut them on the waterjet, or how cool they look, I’m not about to give up the tradition of carving them the old fashioned way with my friends and family.”

Contact Information

Tom Monroe
FluidCut
Email FluidCut
1-586-293-9100

How To Use Diamond Tool To Cut Steel In Micro Machining?

The diamond tool is commonly used in micro-machining as it can withstand the micro hardening of the workpiece surface during micro-machining. This micro-hardening creates enough resistance to break the tool bit easily in micro milling, but not a diamond tool. Micro-machining using diamond tool could be performed at high speeds and generally fine speeds to produce good surface finish such as mirror surfaces and high dimensional accuracy in non-ferrous alloys and abrasive non-metallic materials.

However, if a diamond tool were to be used to cut steel, one of the most common engineering materials used in industries, the diamond tool will face severe tool wear. While diamond only softens at 1350 degree Celsius and melts at 3027 degree Celsius, and is also the hardest material in the world, it has a weakness. Diamond succumbs to graphitization, which means that it will change its crystal structure to graphite crystal structure at 200 degree Celsius in the presence of a catalyst metal such as carbon steel and alloys with titanium, nickel and cobalt.

There have been various attempts to improve the tool life of the diamond tool while cutting steel so as to improve the efficiency and profitability of this operation. Such processes include micro-cutting the steel workpiece in a carbon-rich gas chamber as well as a cryongenically cooled chamber. However, these methods require costly equipment modification and restrict direct supervision of the micro-cutting process.

The latest breakthrough came when the diamond tool was subject to ultrasonic vibration during micro-cutting. It has been shown that a diamond tool subject to ultrasonic vibration can cut the steel well enough to produce a mirror surface finish with acceptable tool life. The ultrasonic vibration at the diamond tool tip allows the tool face to cool down considerably during the cutting process and delays the chemical reaction between the diamond tool and the steel workpiece. As a result, the diamond tool life is increased by a few hundred times.

For example, a single crystal diamond tool with feedrate 5 micron/revolution, cutting speed zero to 5m/min and depth of cut 10 micron was attached to a ultrasonic vibration generator so that the diamond tool tip vibrated about 4 microns while it was used to cut stainless steel. The mirror surface finish of the cut steel surface was measured at 8 nm Ra!

With more and more machining companies moving into the niche micro machining field, such ultrasonic vibration assisted cutting can only help the progressive company to achieve process leadership and innovative differentiation.

Author Ken Yap is a director of Suwa Precision Engineering Pte Ltd in Singapore and represents metal stamping, precision machining, miniature precision balls and PCB manufacturers from Suwa, also called "The Oriental Switzerland" in Japan due to its Swiss resemblance for rich watch-making industry, its mountainous terrain and its precision component making industry.

About the Author

Ken Yap is a director of Suwa Precision Engineering in Singapore, and represents precision component manufacturers from Suwa, Japan. He is also a partner in Attisse Pte Ltd providing business consultancy and research services to Japanese investors.

Since we are dealing with machines that do work for us, we need to control those machines somehow.  We need to control them for safety reasons as well.  If you give a machine improper commands it can easily get out of control and cause harm to you or the part you are machining.  We want to give appropriate commands to our machines, at appropriate times so they are not "out of control". 

The language that these machines use is called G-code.  G-code has been around since the early 60’s.  There are a number of variations of G-code, but most are very similar to one another.  See the previous section for a sample of G-Code. 

We will need to use a computer to talk with our CNC machine.  Our computer will send signals to our CNC machine.  In-between our computer and our CNC machine sits a controller.  A controller converts commands into signals that are used to control the motion of our machine.

As these signals are sent out of the controller, they go to either stepper or servo motors.  This is how we create motion.  These motors drive our various axis on our CNC machine.  While we are moving our axis, there is generally a cutting tool of some sort removing material.  This is the machining process coupled with CNC.

Here is a brief description of the two types of motors generally used in CNC:
Stepper motors:
Simple design
Easy to use
Generate torque at low rpm
Do not know their position in relation to the program

Servo Motors:
Generate torque at high RPMs
Generally need gearing of some sort to be effective
More sophisticated
Can maintain their relative position, thus, they can be more accurate

Machine Controllers
Controllers generally stand alone near the CNC machine.  They act as a translator between your control computer and your CNC machine.  Generally, they add quite a bit of cost to a CNC machine as well.  Controllers can cost anywhere from $1000-$20,000 or more depending on their sophistication.

Just about any topic that is covered about working in a shop should start with safety.  Your safety and the safety of others should always be at the top of your mind.  CNC is no different then any other shop topic.  In fact, the highest levels of safety awareness should be maintained when using a CNC machine.
CNC machines don’t have a mind of their own.  A computer gives them a command and they execute it.  They don’t care if they are cutting steel, aluminum, wood or your hand.  They don’t differentiate between materials.  You need to be aware of this.

When you are learning CNC you should take it slow.  Do tests on a small scale, then watch and learn what happens.  For example, why don’t you let your machine “cut air” for a while when you first get it.  You don’t need to put it right to work cutting material.  Why not create a simple program, and let the machine cut the air instead of material.  Better yet, why even run the spindle during the test.

Every CNC machine has quirks that you need to learn.  Every CNC machine has a different working envelope.  Every CNC machine is just a little bit different then the rest of them.  It is in your best interest to learn your machine before you put it to work. 

Generally, with a CNC machine, we are machining something.  While machining, “chips” are being thrown off.  Sometimes at a very rapid speed.  Here is where safety glasses, face shields and material barriers come into play.  Use them!  The machine doesn’t know you are standing there.  In the words of every boxing ref before a match, “protect yourself at all times!”

A few ideas to keep you safe in the shop:
Always read the instruction manual before using your machine
Always follow manufacturers recommendations
Always wear safety glasses
Wear appropriate Personal Protective Equipment for your job
Use shields and barriers while machining when it is appropriate
Test your machine before full production
Perform proper and routine maintenance on your machines
Perform checks on your machine for wear and damage

Always think safety!

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 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.

Here are some advantages of using Design Software:
Saved file you can use over and over
Transfer the design to others
Can use exact measurements
Repeatability in design

Here are some disadvantages of using Design Software:
Cost money
Takes time to learn
May not be the quickest way of making something if it is a “One Off”

My Definition of Design Software
If you are an engineer, you will probably consider CAD Software as design software.  That is true.  But what I am talking about here is “Creative” Design Software.  These software packages are used by creative types for print, web design and logo design.  This software is great for creating designs that flow and are artistic in some way.
Design software can be boiled down to what it is good at.  If you want to make a square with a hole in it or a triangular gusset, then CAD type design software works great.  If you want to cut out a Cowboy on a Horse, then “Creative” Design Software is the only way to go.

Here are some examples of work for “Creative” Design Software:
Plasma Art
Router Art
Signs
Engraving

Quick Explanation of the Process
This is how I view CNC.  I break it down into simple steps that I can remember.  Now, they all interact, but it is good to keep them in boxes for simplicity sake.  I also like to keep them in a logical, progression type order.  Here they are: Design, CAD, CAM, Control and Machine.
Today you are going on a journey.  You are going to learn about the basics of CNC.  I hope you are as excited as I am about this topic. 
I have been using CNC equipment in my home shop for six years now.  The technology gets better and better every year.  The software gets better every year.  At one time large companies could only afford this technology.  Now there are hundreds of thousands of these machines working in garages like yours and mine.

There are basically five elements to a CNC Project that you need to know:
Design – thinking and planning what you want to build
CAD – translating it into the computer
CAM – converting it into machine language
Controlling – directing your machine’s motion
Machining – building the part to specifications

These five elements are really the building blocks to a CNC project.  As you see them above, that is generally the order people associate them in.  For example, you can’t control until you have a design.  You can’t use your CAM software before your CAD software.  One of the main things you need to address is how these elements interact with each other.
Right now this may seem confusing.  Over time, it will seem very basic.  The more you use these elements with one another, the more their order will become second nature.

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 shapes were going to be my new 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 had just found a new hobby, 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 plasma cutting all those parts my wrist really began to hurt.  While welding professionally there was always the threat of Carpal Tunnel Syndrome.  Welders are constantly afflicted by this injury and others because of Repetitive Motion.

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.

That is when I began investigating Hobby CNC.  I call it “Hobby” CNC, because that is how I found it.  There were small groups of enthusiasts on the Internet that were building these machines for the fun of it.  I thought this was the ticket. 

My Initial Thoughts on CNC…
I thought, “If I could build a CNC Plasma Cutting Table?”
I could hook my plasma cutter to it
Create a program of the part I wanted
Cut out multiple parts to my hearts content
Save a lot of time
And Finally…
Save my wrist from the dreaded Carpel Tunnel Syndrome.

I really wasn’t scared of the technology to start with.  I grew up in fabrication shops across the Midwest and had seen these machines in action.  These machine “Operators” were always held in high esteem at the shop.  They always made more Money and always had as much Overtime as they wanted.  I decided if they could do it, I could do it.

CNC hobby projects were not cheap at the time.  I figured I would have to invest $4,000 – $5,000 to build my table (they have come down considerably).  Keep in mind this was in 2000-2001.  For some reason that didn’t scare me off.  I always liked a good challenge and this was it.  With blind faith, I ordered up a CNC Controller and went down to my local steel yard to fill the back of my truck with steel.

Little Did I know…
There was a steep learning curve with CNC.  Building a frame for the machine is only a small part of the project.  Today it is much easier.  The software, components and suppliers are better.  There is an entire cottage industry that has sprung up around CNC to support it.  Some of the best people in the world make their livings servicing CNC Hobbyist needs.

For some reason I figured if I just build this machine it would spit out parts whenever I wanted it to.  Simple, Simple, Simple ran through my head.  Over time, I started to get it.  I didn’t have a teacher, but I started to learn the ins and out of what I was doing.

Other things I had to learn along the way:
CAD Software
Designing Parts
CAM Software
Preparing parts for machining
Simulating Machining
Machining Basics
Cleaning parts

There are multiple CAD programs available for design.  Generally people become familiar with one and stick with it.  As far as selecting the right one, my advice is this.  Most software companies have a free trial.  Thirty-day trials are common.  Take advantage of these trial periods and test the software out.  Then at the end, decide if you want to try another software or stick with your best one.  I would advise you try out at least three different packages.

The one you select will probably have to do with you liking the interface or finding it intuitive.  Keep in mind it may work for you now.  A simple to use and understand interface probably has some limitations for your designs.  The very best programs are complex with many tools that give you the most control.  I have found that I start with a simple program and outgrow it.  At some point I move up to the next level of software.  This usually means a higher price as well.

Tools in CAD
Inside of your CAD program, you will have various tools that you can work with.  Many of these tools speed up your design times and make you more efficient.  Each CAD program will have similar tools and then unique tools that are only available with their package.  These specialty tools are one of the ways software manufacturers differentiate themselves in the marketplace.

Types of CAD
There are different types of CAD out there.  These are the ones I deal with from time to time.  2D CAD, 2.5D CAD, and 3D CAD.  Here are some quick explanations of each type.

2D CAD
2D CAD is generally on the low end of CAD software packages.  2D CAD is most often vector based.  The design consists on the X and Y-axis only.  The designs are made up of lines, circles, ovals, slots, curves, etc.  There is no “depth” to the design.  Only the outline of the part is visible, to put it in a different way.

2.5D CAD
All of the same descriptions above apply, but the design is prismatic.  By that I mean it has the depth of the material.  There are Z levels, but they are on singular planes.

3D CAD
3D CAD is on the high end of CAD software packages.  3D CAD can be solid based, wire frame based or nurbs based.  The design consists on the X, Y and Z-axis.  The designs are made up of lines, circles, ovals, slots, curves, etc, but can also include Spheres, Pyramids, Torrids, Cubes, etc.  There is depth to the design.  The design can be rotated around 360 degrees.  The design is an accurate description of what the part would look like if produced in the real world.