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Posts Tagged ‘Control’

CNC Routing (Computer Numerical Control) is where a computer-controlled, routing mill is used for intricate or large volume production runs where a high standard of replicated product is required. CNC routing may be used for metal milling but it is more commonly used for woodworking and cabinetry manufacture though other materials such as plastics and nonferrous metals can be worked on also.

A CNC router is able to deliver an extremely standard of accuracy and provide excellent detail. As it is largely a computer-controlled process, the milling is carried out at high speed and the whole production line is capable of producing repetitive cuts providing a very high standard of product finish.

CNC routing is recommended for customers who are looking for high-volume production jobs where there is a lot of repetition and identical unit production, or single-unit customers who need a very high degree of detail which may not be available cost-effectively where a human operator is required to make the cuts. As the CNC router is programmed with the cuts and milling scheme, customers are also able to use the program for a production run, quickly change the program to perform a different production run and then use the previous program again and again for future production runs. This helps to keep the different production runs extremely similar in terms of reproduced design (practically identical if near-matches to the raw material being milled is adhered to) and this also helps keep production costs down even further.

Typical CNC routing jobs include engraving, customized cabinetry cuts, large production jobs with repetitive cuts, creating through holes and blind drilling and of course, routing. CNC routing produces signs which are a much better alternative to sand-blasted signage and especially if you do not want any textured surface exposed to the elements and which will attract dirt and grime. CNC routed signage is widely used for historical markers, golf courses, building names, internal room and area signage, markers for residential and commercial development and typically employs channel cuts (known as “hog-out” in the trade) to produce one-piece, high quality product.

Less well-known uses include making military shields and emblems; monuments and historical markers; boat and marine environment signage as well as dedication signage. While the materials used in the construction of these more esoteric products may not be wood, they do provide a good mental view of how CNC routing can help a client to use non-wood materials where either use or environment precludes wood from being used.

Ordering a CNC routed product is simple and easy – the design files are created either by you or your designer and provided to the milling partner who will conduct the work. They take the design as a computer file which is known as a “vector file” – this saves information in a format which the machine understands and can interpret to reproduce the design using the raw materials. The CNC router then cuts the “blank” which is the exact shape of the finished product and it is passed through a priming and sanding process and will have the backing material which will be the color of the finished product detail. An adhesive coating is applied which coats the entire blank and needs to be left to “cure” or set. Finally, the CNC router makes the cuts and milling procedures to remove the coated material to expose the underlying material which will form the finished design once the protective film is removed.

CNC machining is quite common nowadays in manufacturing operations everywhere both for high production, high volume component manufacture as well as complicated small volume manufacturing where parts may have very complicated geometries and sophisticated features. During such manufacture using CNC machining processes, manufacturing engineers tend to pay very close attention to important aspects of part programming, tool choice and tool wear control, tool path control to avoid CNC tool crashes, the very important parameters of machining feeds and speeds, etc. And rightfully so, because every one of the parameters listed heretofore is very important to produce parts of the highest quality consistently.

 But one parameter that is seldom given its due importance is coolant control in CNC machining operations. And it is fairly easy to overlook since generally coolant is not changed after every set of parts is manufactured. Additionally, manufacturing engineers tend to delegate coolant management to maintenance personnel. However, as you will notice in what follows, that proper coolant control is important not only for part quality, but it can also influence the bottom line cost of production.

One of the characteristics in quality control of machined components is the surface finish that is generated. Poor coolant quality results in low quality surface finish. This is because the heat generated in machining is not easily carried away from the machined part as well as from the machining tool. Spent coolant or coolant that has lost its potency to cool can thus cause havoc in part quality. Additionally, poor coolant quality can cause pre-mature wear of the machining inserts and they will have to be replaced more often in order maintain sharp edges during machining. Insert changes are costly both from the point of view of insert costs as well as machine down time during insert changes. Poor coolant quality can cause drills to break when drilling deep holes. Now this can become a real problem if it is a one piece quantity of an expensive part, because now the broken drill will have to be removed and then the operation resumed. This will add significantly to part costs.

Thus it is important to ensure that coolant quality is properly maintained to produce parts with acceptable levels of surface finish and to ensure longevity of tool life in order to reduce part costs.

Day 5 is all about CNC Control. CNC Control is made up of three parts. The CNC Control Computer, CNC Control Software and the actually CNC Controller. The CNC Control Computer can be basic and inexpensive. The computer will live in a harsh environment that includes dust and dirt. The…

I would like to know which model of CNC control system is easiest to both program and use and on which machine models, including both lathes and milling machines.

The Control Computer generally resides in the shop somewhere near the CNC machine it is controlling. Control Computers don’t have to be the top of the line, every bell and whistle type of computer. These are the workhorses. 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. It takes G-Code and turns it into signals that it transmits 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 usually 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.

Here is my strategy in a nutshell for Control Computers. The dirtier the job, the less money I spend on the computer. My plasma cutting computers are bought in the $40 range. They eat a lot of dust and dirt. I blow them out frequently. My wood routing computers are in the $100 dollar range. My milling machine computers usually are in the $200 range. Truth be told, they all last a very long time if you keep dirt, dust and plasma smoke out of them.

How is the CNC Control Computer used?

The control computer has the control software loaded on it. You start up the control software then load up the CNC Program you created. When you do this, the G-Code will be visible and ready to go. Once you prep your CNC Machine and zero it out, you can begin your “cycle.” A cycle is usually completing one CNC Program, which is a machining sequence. You will also hear the term “Cycle Time” on the professional side of CNC a lot more. The quicker you can get the cycle time, the more parts you can make. And yes, that translates to more money.

Back in the good old days of Home CNC, everything was transferred on a disk. Now I have seen people include their Control Computers on their home computer network and transfer the files needed wirelessly. At a very minimum, get a good jump drive and transfer things back and forth that way.

CNC has become a very popular hobby and more and more people are starting to hop on the band wagon of CNC. Its a fun hobby and easy to do from your very own home with just a little elbow grease and creative mind.