CNC, stands for Computer Numerical Control, applies to the machine control system but erroneously used as a replacement term for NC (Numerical Control). CNC-machining is a fully automatic, subtractive digital manufacturing technology, whereby the computer software drives the machine tool movement.
CNC is a generic term, used to control a wide range of modern machinery ranging from milling, lathe, grinder, laser cutter, router, edm, wirecut etc. CNC machining has a leading edge over conventional machining, as complex parts and ergonomic shapes can be machined with ease. We frequently use CNC Milling machines and Lathe machines to produce accurate and functional parts with excellent physical properties.
The basic process of CNC operation starts from a CAD model. A CAD model, also known as Computer Aided Design, is a digital representation of a physical part. The CAD model is a core of any manufacturing operation, because it represents the true reflection of the finished product. Any flaws in a CAD model will be reflected in the end-product, this rule applies to both subtractive and additive technologies.
Once the CAD model is fully optimised, it is transferred to the manufacturing software known as CAM software. The CAM software (computer-aided manufacturing), translates the CAD file into the numerical data (also known as G-code). It includes the set of instructions, and known as the back-bone of machine tool functionality. All the machine specific parameters such as tool path, speed, feed rate, step-over, rpm etc can be controlled autonomously through the machine coding.
CNC machining is a form of subtractive manufacturing, means the process starts with a solid block of raw material and extra material is precisely removed by sharp cutters. Machining process is entirely opposite to additive manufacturing, whereby material is added layer by layer.
Much of modern day machining is carried out by computer numerical control (CNC), in which computers are used to control the movement and operation of the mills, lathes, and other cutting machines.
A typical 3-axis CNC Mill consist of a table to hold the work piece that moves in X and Y axes. This workpiece is formed into a finished shape by cutting step by step with a sharp tool, known as a cutter.
This cutter is tightly clamped in a spindle which spins at high RPM and moves vertically up and down or in a horizontal direction depends upon the machine configuration. Generally in 3d machining all X, Y and Z axis move simultaneously.
For complex 3D parts, 5-axis machining is used where machine head and table can also swivel in real time. All these machine movements are controlled by cutter path which is generated by CAD/CAM software and transferred to the machine controller in the form of numerical data also known as G-code.
Generally, a Lathe machine is used for machining cylindrical components, also known as turning operation. The major difference between Lathe and Milling machine is, in Lathe machine work-piece is held in a rotating chuck and cutting tool is fixed to the tool post of the machine carriage. The general process of turning involves rotating a part while a single-point cutting tool is moved parallel to the rotation axis for turning the diameter, or perpendicular to the axis, called facing operation.
CNC lathe machines are widely used for mass production of turning components. It is preferred to machine cylindrical parts on a lathe machine to achieve high accuracy and surface finish. Lathe machines can perform multiple operations such as Turning, Boring, Facing, Threading, Drilling, Parting, Grooving, knurling, Reaming, Tapping.
ABS (Acrylonitrite Butadine Styrene) is a general purpose rigid thermoplastic with a combination of properties that make it ideal for the wide range of rapid prototyping applications.
PolyCarbonate (PC) is a tough and durable, transparent engineering thermoplastic notable for its high impact resistance, temperature resistance and optical properties.
Acetal also known as POM (PolyOxyMethylene) is an engineering thermoplastic often used for precision components that require high stiffness, low friction and excellent dimensional stability.
Also known as PMMA (PolyMethyl-MetaAcrylate) is an amorphous thermoplastic material with very good optical properties. Acrylic is often used as a glass substitute. Acrylic is hard and stiff, but brittle and notch sensitive.
Nylon is a generic designation for a family of synthetic polymers known generically as PA PolyAmides. Nylons (Polyamides) comprise the largest family of engineering plastics with a very wide range of applications. Nylons are generally Strong, Tough and Wear Resistant.
PolyPropylene is a semi-opaque thermoplastic widely used in a variety of applications. Polypropylene has good resistance to fatigue. PP offers a combination of outstanding physical, chemical, mechanical, thermal and electrical properties.
Polyvinyl chloride (PVC) is a solid plastic material made from vinyl chloride, it can be made softer and more flexible by the addition of plasticizers. PVC is one of the most commonly used thermoplastic material used in building and construction.
Polytetrafluoroethylene (PTFE) thermoplastic polymer, which is a white solid at room temperature. Teflon is the trademarked brand name for PTFE owned by Chemours, a spin-off company from DuPont.
Aluminium is the most widely used non-ferrous metal. Aluminium is a soft, Durable, Lightweight, Ductile and Malleable metal with appearance ranging from Silvery to Dull Grey, depending on the surface roughness. Aluminium naturally generates a protective oxide coating and is highly corrosion resistant.
Stainless Steel is a generic term for a family of corrosion resistant alloy steels containing at least 10.5% of Chromium. All stainless steels have a high resistance to corrosion. The ease with which it can be steam-cleaned and sterilised, and the absence of the need for surface coatings, have prompted the use of stainless steel in kitchens and food processing plants.
Mild Steel is the most common form of steel, widely used in various industries. Mild steel is a form of low-carbon steel comparatively having low amount of carbon contents ranging from 0.05 to 0.25%, making it malleable and ductile. It becomes malleable when heated, and so can be forged.
Copper is one of the few metals that can occur in nature in a directly usable metallic form. Copper is a very durable, soft, malleable and ductile metal with very high thermal and electrical conductivity. It conducts electrical current better than any other metal except silver. Copper is recyclable without any loss of quality, copper's recycling rate is higher than any other engineering metal. Copper is used mostly as a pure metal, but when greater hardness is required, it is put into such alloys as the most well-known copper alloy families are brass (copper-zinc) and bronze (copper-tin)
Brass has long been a popular material for decoration for its bright gold-like appearance. The most commonly used colour of brass is bright golden. Brass is an alloy of copper and zinc, in proportions which can be varied to achieve varying mechanical and electrical properties. Brass is commonly used in applications where low friction and corrosion resistance is required. Brass components can often be used without any extra surface protection.
Zinc is the world’s fourth most widely consumed metal after iron, aluminium and copper. Zinc is a slightly brittle metal, and zinc has a bluish white surface appearance. It is brittle by nature, but exhibits good malleability and ductility at higher temperatures and easy to machine. Zinc is primarily used in order to galvanise steel because of its useful anti-corrosive properties and ability to bond well to other metals. Zinc metal is employed to form numerous alloys with other metals such as Brass, bronze, nickel silver are common examples.
CNC Machining offers a wide range of material selection, including plastics and metals. The physical properties of CNC manufactured parts, closely resemble with the mass-produced components, such as injection mouldings or metal castings.
CNC machined parts can hold tighter dimensional tolerances compared to additive manufacturing technologies such as 3D printing. High precision machined components can be directly used for assembly-fitment, without any post-processing work.
CNC machining enhances the capability of producing complex shapes and designs, which are hard to produce by conventional machines. The organic geometries can be machined as efficiently as flat surfaces, thanks to the advanced controllers fitted in CNC machines.
The latest development in CNC machining, provides an ideal solution for small to large orders since it can manufacture hundreds to thousands of functional parts in a short period. CNC machined plastic and metal custom parts can be supplied in as little as 10 days.
An accurate movement of machine tools is controlled by NC programming, makes it possible to deliver precision results repeatedly. An advancement in work-holding devices and tool cutters also help to produce consistent results again and again.
CNC machining can be very efficient and perform as fully autonomous operation, thus reducing the labour cost. Once the digital parameters are uploaded onto the CNC machine controller, it can run by itself with little or no human intervention.
Engine & chassis components, lighting fixtures, dashboard parts, auto electrical parts, suspension components, bushes, valves, motorsport components, steering parts, exhaust system, electric vehicle parts, moulds for auto parts.
Injection moulds, sheet metal tooling, machine tool parts, extrusion dies, jigs and fixtures, die casting moulds, gauges, special purpose machines (SPM), robot manufacturing and automation products, conveyor system parts, gears, bushes.
Farming machinery, feeder, sprinklers, sensors, tractor parts, harvesting equipment, solar devices, drones, fruit picking machines, gardening tools, replacement parts for farming, spraying system, irrigation components, pump, spare parts.
Casings and enclosures, heat sinks, sensors, printed circuit board (PCB), RFID tags, Electrical connectors, motor housings, remote controls, fans, mobile phones, exhaust fans, LED lighting, TV components, CCTV, computer or laptop parts.
Communication equipment, radars, wireless transceivers, drone parts, engine parts, rapid moulds for aerospace parts, cockpit components, military satellites, fasteners, lighting, seating parts, Panels, wind-turbine models, rotors.
Air conditioners, vacuum cleaner, dryers, washing machines, juicer, heaters, freezers, refrigerators, microwave ovens, food processors, deep fryers, blenders, coffee machines, electric kettles, IOT devices, cameras, computers, telephone, consoles.
Hardware items, architectural items, construction equipment & tools, cladding, scaled models for building concept design, window & doors, taps, plumbing items, railing, facades, modular home fittings, extrusions, hardware items, light fixtures.
Surgical equipment, prosthetic devices, masks, ventilators, respiratory devices, x-ray machines, ultrasonic machines, anatomical models, lab equipment, MRI machines, diagnostic devices, medical device housings, hospital equipment.
Scaled concept models for visual display of boat, car; bus, train; ship, aeroplane; or any other type of transportation vehicle. Doors, panels, railing, extrusions, body parts, lens, dashboards, seats, fasteners, headrest, brakes, lighting, cabins.
STEP file is our preferred CAD file format for CNC machining, even for 3D printing. Please do not submit STL file for machining, as we can't machine on STL files due to triangular mesh geometry, also it becomes very difficult to modify STL files.
We prefer 3D CAD files in one of these formats:We have a wide range of materials available as outlined below.
For Plastics:Milling is a subtractive manufacturing process, whereby the workpiece is clamped on the machine table and a rotary cutter is used to remove an excess material. For manual machining, cutter and machine table movement is controlled manually however in CNC machining these movements are controlled automatically using NC code also known as G-code.
Lathe Machining:Generally Lathe machine is used for machining cylindrical components, that's why it's also known as Turning operation. The major difference between Lathe and Milling machine is, in Lathe machine work-piece is held in a rotating chuck and cutting tool is fixed to the tool post of the machine carriage.
CNC machining is a subtractive manufacturing process; it means the end-product is produced by removing extra material from the work-piece.
CNC machining is one of the most commonly used manufacturing technology to produce end-use products, without sacrificing material properties.
On the other hand, 3D Printing is a form of additive manufacturing; it means material is added layer by layer. 3D printing is leading the way in prototyping industry,
especially at the early stage of product development due to quick turnaround and affordability.
Setup cost is higher
In CNC machining process, initial setup cost is higher, it's not as simple as printing on 3D printer.
Firstly, you need to use CAM program to prepare the machine code (also known as NC code), which is used to control, automate, and monitor the movements of a CNC machine.
However, once you have a NC code prepared, it can be used again and again to produce identical parts.
Sometimes rigid and purpose built work-holding devices required, depends upon the part geometry.
Hollow parts are hard to machine
Contrary to 3D printing, it's difficult to machine voids or hollow parts. If it's necessary, then parts need
to be cut into sections and bonded after machining the internal voids. The undercuts are also challenging to machine.
Human intervention
The machine operator has a significant level of control over the accuracy of a CNC machining project. Careful
attention is required from the machine operator to ensure that all the product features are machined to the full extent.
It's challenging to machine complex shapes accurately and effectively. It all starts from product designing stage, if product is designed with fundamental machining concepts in mind, it makes machining process lot smoother and will henceforth improve the product quality and reduce cost. Machining process has its own limitations, so if a part has no undercuts or voids or narrow features, we call it a machining friendly part.
You can consider the following points to design machining friendly parts:
When considering the CNC operations, they have been spread over a wide range, such as turning, milling, drilling, 3D printing, electric discharge machining, laser jet and water jet cutting. A detailed explanation of these mentioned types of CNC operations are presented in this article.
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Between the design phase and the marketing phase of a particular product or an equipment, there are several steps that we should follow. One of the key milestones of the product manufacturing process is the selection of the most appropriate process for the production.
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Technical Data comparison of various prototyping materials, including Mechanical, Physical, Thermal & Electrical properties compared in an interactive sliding scale. A handy PDF property chart of plastic materials can be downloaded from this page.
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