CNC News | CNC Future

People new to product and part design need to know that CNC means ‘computer numerical control’. It generally means a computer controller for a cutting machine such as a lathe, milling machine, water jet (waterjet) cutter, or laser cutter, that reads G-code instructions and steers the machine cutting head - a powered mechanical device, typically used to fabricate metal components by the selective removal of metal. The most important benefit offered by a CNC machine is improved automation of part manufacturing. The operator intervention related to producing work pieces can be reduced or, on some machines, altogether eliminated. A second important benefit of CNC technology is consistent and accurate work pieces. This means that once a program has been verified, two, ten, or one thousand identical work pieces can be easily produced with great precision and consistency. Another reason why CNC machining shops have become popular is flexibility. Since these machines are run from computer programs, running a different work piece is almost as easy as loading a different program and different target material. Once a program has been verified and executed for one production run, it can be easily recalled the next time when the work piece is to be run . This leads to yet another important benefit, fast change-overs.
Since these machines are easy to setup and run, and since programs can be easily loaded, they allow short setup time. Various tools making use of CNC variants are: Drills EDM’s Lathes Milling machines Wood routers Sheet metal works Hot-wire foam cutters Plasma cuttings Water jet cutters Laser cutting Oxy-fuel At www.emachineshop.com , the online machine shop makes a wide variety of 2D and 3D shapes. CNC milling may be used to create engine components, custom and mold tooling, complex mechanisms, enclosures, etc. One advantage of CNC milling at eMachineShop is the cost effectiveness for short runs, with complex shapes cut from sheet, block or bar stock material. As you design parts, eMachineShop suggests you use the free eMachineShop software to try various combinations of machines and processes, along with alternate material choices to optimize your designs. Machining involves a material that is usually removed by both the ends and the side of the cutting tool. In CNC milling the cutting tool usually rotates about an axis that is perpendicular to the table that holds the material to be cut. Cutting tools of various profile shapes are available including square, rounded, and angled. A wide variety of part shapes and geometries are possible in this fashion. Keep in mind that CNC is not a total “computer solution.” You should be aware that CNC milling requires not only software program tooling but in many cases work-holding jigs. This is why machine and material optimization - easily done within eMachineShop’s free CAD software - is so important to achieving the best possible price/performance result.
 
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“At this time the vendor will view the given information, usually comprised of dimensions of part and type of material needed as well as temper and strengths of the application needs for the part. There are also instances where some type of exterior or interior plating may be needed; this too is taken into consideration at the time of quoting.

These are some of the necessary tools needed to properly quote the machined part for production in the machine shop. Other areas of information include number of pieces required and lead time for production. At this time a quote for manufacture will be offered to the customer with a valid lead time and price for production as asked for in their original RFQ (request for quote). The buyer will at this time compare to other possible quotes and choose from them the best one that fits his/her criteria.

A Purchase Order is then received for the part quoted from the customer to the awarded vendor. The information on the purchase order will provide the vendor with part number, quantity ordered and delivery date needed by along with the price quoted by vendor. Some customers will even go a step further and put the vendors quote number on the purchase order for confirmation purposes. The vendor will now compare the purchase order to the quote offered and make sure that all information meets the quoted details and either accept or decline the P.O. This process is the contract review phase.

The challenge now is to determine the most efficient method to manufacture the parts per the print specifications i.e. CNC machining, fabricating, stretch forming, hydro forming. A procurement specialist for the awarded vendor will now begin the task of sending out their own RFQ’s for material and any outside processing that will need to be done, as well as creating a job router for the part for traceability purposes. Aerospace machine shops should hold quality requirements per the AS9100 standard, which requires material tractability throughout every step of the machining process. This job router has all the information from the purchase order on it and will travel with the material from beginning to end. Once the material has been ordered and received it will usually go through a saw process determined by a machine programmer. Now the cut material will go to a designated machine for shaping, either by manual means or CNC (automatic). After the part has completed its time at the machine, it will go through a vigorous inspection process to assure the customer a part that complies with the information provided. Now the part will go to any plating or other outside processing and return for shipping to customer with the satisfaction of knowing that all needs have been met. 100% first article inspection reports are and all other documentation per AS9100 are sent with parts to the customer for final review.

Quality systems are a paramount function of any and all manufacturing of parts. Quality systems such as AS9100 and ISO9001 direct a company to uphold some of the highest quality standards in the manufacturing industry. A company’s quality statement and quality policy should be know and respected by all employees in the organization. Quality starts form the top levels of management and flows downward to the shop floor. “

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The development of computer numeric controlled (CNC) routing, using affordable personal computers has already begun to revolutionise all aspects of the woodworking industry. In so doing it has created new opportunities for large and small businesses as well as for individual craftsmen.

CNC is a technique whereby the movement of a router head is controlled by instructions from a computer. These instructions come from a computer program or list that the user keys into the CNC 860 console or into a computer as ISO standard commands called ‘G’ codes.As an example, the code G01 X100 Y100, instructs the head to move in a straight line to a point horizontally and vertically 100mm away from its starting position.

The CNC 860 The Trend CNC package is based around the Elu/DeWalt CNC 860 Machining Centre, which has a machining area of 860mm x 860mm x 90mm. These dimensions relate to the three axes, X,Y and Z (width, length and height). Each axis is served by a separate stepper motor, controlling the movement of the routing head. Two head options are offered: a modified portable router or a continuously rated, high cycle motor, that provides improved performance for intensive machining applications.

Programming directly in G-codes through the console can be time consuming. To assist the operator, a PC software application called CNCTalk is included with the machine. This is a basic computer aided design (CAD) application which runs under DOS, the original PC operating system before Windows. It is useful for intermediate applications like cutting out irregular shapes. However, to gain the maximum versatility from the CNC 860,Trend’s Open Sign System Software for Windows is the most effective solution.

OSS consists of two separate software applications: OSS Draw which provides the drawing tools to create any shape or sign, and OSS Work which handles all the routing and tooling-related parameters like depth and offset. Graphical simulations are shown for all tool parameters enabling the user to perfect a design before routing any material.

Sign-writing As an example of how these products work together, the method of producing a simple sign is shown, incorporating two different lettering styles and a graphical logo. Having launched OSS Draw, the first step is to draw a box or boarder on the screen to indicate the overall area of the work. This can be either a simple rectangular boarder or a more decorative one. This border then needs to have a depth assigned to it. This is done by using colours to define the depth of each area.

The logo is then created using the drawing tools within OSS Draw. The words are keyed in using the text function. Again, colours are assigned to each area to produce a graphical representation of how the finished sign will look. The next task is to define the routing parameters. In the example, the red and blue areas of the logo and the lettering have been assigned a depth of 5mm and the green area assigned a depth of zero. The same dialogue box lets you specify whether a letter or object is engraved or routed through the material. The cutter profile that will be used can now be defined. With lettering, particularly serifed fonts, the cutter used needs to have a small diameter, perhaps 3mm. However, to achieve a 5mm cutting depth this will have to be routed in several passes.

A simulation of the cutting path is now drawn on screen. Having then created a G-code file of the sign ready for the CNC 860 to cut, the file is downloaded to the CNC 860. The design can now be routed, the material being held on the bed by an adaptable clamping mechanism. From the simulation, the path that the tool will take is known allowing a datum point to be set using the zero key on the console, and the program 8 INProfile is run using the start key. This type of routing operation takes around 20 minutes to complete and requires no further involvement by the machine operator. Other accessories Sign-writing is just one of the many complex and wide ranging routing operations that can be carried out using the OSS and CNC 860 package. OSS also has a range of tools for drawing component shapes and profiles directly or with an electronic sketchpad (graphics tablet). Vacuum Clamping To reduce the through-put time for this kind of operation, the CNC 860 can also be used with a vacuum bed. Trend offer a complete range of affordable vacuum pumps and jigmaking accessories to enable all CNC users to produce a highly automated production system to suit their own specific requirements.

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I am building a CNC router. I have Autodesk Inventor to design all my parts and stuff. The only thing is there is no way to save it as a DXF file directly from Autodesk as far as i know. And i found a program but you have to pay for it. Im just wondering if there is a way to save a part as a DXF file that i dont know about.

Thanks and have a merry christmas

Justin Hulbert

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This pertains to CNC milling machines and their control system.

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i have 2 years experience and am just tired of my shop. does any one know of some good shops to work for

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Upgrading my shop by buying a cnc mill so I can produce in house. However, I want to be able to mill steel, stainless, titanium and aluminum. The steel and titanium I know are lower rmp speeds for milling due to hardness. What is the minimum spindle rpm allowable so that I can buy a mill that will be capable of milling all of the above listed material?

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Does anyone know of a place that I can get used cnc mills that are big enough to make car rims for cheap? I don’t need anything that cuts very fast. Speed doesn’t matter, cost does.

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High speed machining is a proven stipulation characterized by low cutting forces and high metal removal. High Speed Milling is a technique used in the CNC Milling Industry that combines high spindle speeds with increased feed rates. This results in a high chip-forming rate and lower milling forces, producing an improved surface quality and closer tolerances. In high speed milling, the electronics can make all the difference. The right CNC coupled with other elements of the control system can let a slower machine mill a given form faster than a machine with a higher top feed rate.
1. High Speed Uses
High-speed CNC milling is used, for example, to machine the titanium rotors of the first high-pressure compressor stages of the EJ200 engine. High speed CNC milling allows cost-effective milling of the airfoil geometry from the solid. By subsequent finishing operations the planned surface finish is achieved. The CNC milling which caters to high speed must be structured with an axis movement system that is suitable for machining.
2. Axis Movement
The high-speed CNC milling machines required for the process must be fitted with an axis movement system suitable for machining blisks, which should be at least 5 axes simultaneously, depending on the milling task involved and an efficiently high-speed control system.
3. 3D Surfaces
High Speed CNC milling machines working on 3D surfaces in any materials produce a finer surface finish and higher accuracy in less time that the traditional milling machine. Acceleration is the most critical factor that affects the high speed machining. Since one or more axis are always increasing or decreasing velocity in a 3-D cut, ultimate feed rate is directly related to acceleration
4. What Can A High Speed Control Possibly Do?
A CNC milling machine which possesses a higher structural stiffness has a greater potential acceleration rate. Box shaped high speed CNC milling machine, like Bridge and Gantry is the mostly widely used types of High speed CNC milling tools. The overhead type Gantry exudes the highest stiffness, acceleration and accuracy among other high speed CNC milling tools. Due to its scalability, this machine type is available in sizes to match the work piece, from small to large.
In usual terms, it simply gives you the ability to finish one task faster and move along to the next sooner, making work output higher. In drilling and tapping, this can result in faster hole-to-hole times, quicker spindle reversals for tapping, and substantial cycle-time reductions. The most dramatic benefits, though, come in 3D designs machining. Few, drilling and tapping jobs require a million lines of machine codes. In molds, dies, patterns, and prototypes, complex surfaces comprising a million or more line segments are not at all uncommon. Saving just a fraction of a second per move can result in substantial cycle-time improvements.
5. Downsides - When Is Fast Too Fast?
But despite all these benefits, in high milling, the tool path segments can be so short that a machining center moving at a high feed rate can’t accelerate or decelerate fast enough to make direction changes accurately. Corners may be rounded off and the work piece surface may be gouged. Look-ahead is one answer. Look-ahead capability can let the CNC read ahead a certain number of blocks in the program, to anticipate sudden direction changes and slow the feed rate accordingly.
6. Additional Benefits:
- Improved accuracy
- Better fit
- Superior finish
- Better life
- Produce more work in less time
- Improving the accuracy and finish
- Reducing polishing and fitting time
- Tools simply last longer because their chip load is more consistent

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Manufacturers, which produce various steel products, require punching of sheet metal to meet design requirements. Technology has entered the scene of this once manually operated process. This not only increases the speed of production but it gives a new meaning to the term “accuracy” in the positioning of the specific operations. This has been accomplished with the introduction of CNC or computer numerically controlled machining centers.

Punching of sheet metals is a steel fabrication process utilizing ‘tools and dies’. A punch press is the machine which performs the work of shaping and cutting. A turret houses a set of various tools on the machine, depending on the type of punching required.

The punch press, a type of fabricating machine, presses sheet metal against a die with extreme pressure and at very rapid speed of positioning. Sheet metal, now pushed into the die, assumes the shape and design of the specific dye. Cut away, is any excess metal from the newly shaped piece of sheet metal.

Punch presses use hydraulic, pneumatic, or electrical power in their operation. This power exerts immense pressure to press the shape into and perform the cutting of the metal. A piece of sheet metal receives its new form from the taking away of material. Less sheet metal makes a new form. The excess taken away becomes scrap metal for other uses.

A CNC operated punch press typically performs this manipulation process. CNC stands for computer numerical controlled. In the case of a punch press, it utilizes a computer in its operations. The computer directs the action of this press, which contains the tools and their respective dies.

This machine receives different punching instructions from a program written and installed in the computer for a particular application. This enables the machine to go through a complete machining cycle, using various tools and automatically positioning the sheet metal over the appropriate die, at very rapid speeds and with little operator intervention. The accuracy of this process is measured in thousandths of an inch.

A manually operated punch press, for simple punching, with one tool and die set, are still in use today. Large operations with multiple dies and unique specifications rely on the CNC application.

The die portion of a punch press is of very fine tolerances. These are tolerances of thousands of an inch. Pressing sheet metal into a die with a punch means the die does the actual cutting of the metal. The punch, attached to a ram, is a removable piece, as is the die portion.

The die set for sheet metal punching consists of a male punch and a female die. When brought together, with the application of intense pressure, the result is a sheet metal piece as per the specified design.

Punch presses using CNC technology have meant greater volumes of sheet metal production. This process spells efficiency for a company, which means greater profits. This edge is necessary in the competitive steel fabrication companies worldwide find themselves.

Today, there are turret punch presses, CNC types, which perform faster because of technological advances. They can operate unattended and have sheet metal sorting capabilities. New technology constantly raises the mark for performance. Wise steel fabrication companies invest in these applications if it means streamlining of their operations for maximum profit.

Today’s CNC controlled machines can even alert workers who are off-site if something goes wrong in a sheet metal punching process. This allows for unattended “lights out” production capabilities for manufacturers. Telecommunications technology embedded in these computer systems links to users’ phone devices. In essence, CNC technology provides a constant watch over machining of steel.

The use of robotic applications in steel fabrication, including punching, receives continued research and application. Advanced, state-of-the-art CNC technology is the solid future of most fabrication industries.

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