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What Is Precision CNC Machining?
Precision CNC machining is manufacturing components by cutting out and shaping raw materials. Computer-aided Manufacturing (CAM) blueprints and Computer-aided Design (CAD) aid in selecting the correct cutting procedure. These programs are essential during the design phase since they frequently feature comprehensive 3D outlines that guarantee successful part fabrication.
High-precision machining is becoming an essential component of the industrial industry. It necessitates the participation of skilled designers and expert engineers. Designers are in charge of designing and interpreting designs into manufacturing instructions. The machinist then sends the final coded instruction to the CNC equipment in machine language, allowing the manufacturing process to begin.
Steps in the Precision CNC Machining Process
The precision CNC machining processes companies employ are pretty similar, and they are:
Create the Graphical Model
A graphical model is necessary to construct any part. This is performed with the use of Computer-Aided Design (CAD) software. The CAD program allows the designer to build 2D and 3D models of any part for manufacture.
Hand-drawn sketches are commonly used to comprehend the core concepts of a part. The CAD designer then resorts to these sketches to produce the graphical model with precise measurements. There are numerous popular software programs for Computer-Aided Design, both free and paid. Manufacturers might also outsource the design process for any complex design development.
Convert CAD to CAM
Computer-aided design generates a computerized graphical representation of the part. This representation is simple to understand for designers, operators, and manufacturers. However, the CNC machines that make the part do not directly grasp this digital format.
The machine understands coordinates and can move the cutting tool or shift the workpiece based on them. As a result, CNC machines demand that the part design be in a format that includes the essential manufacturing instructions. The readable format for precision CNC machining is created using (CAM) software. The CAM software translates the CAD file format into a format that CNC machines can recognize.
Computer Aided Manufacturing (CAM) software employs two kinds of codes: G and M codes. The G code regulates the cutting tool’s coordinates. The M code manages the machine’s auxiliary functions, such as turning on or off the coolant flow.
Setup the Machine
Once the designs in CAM format are complete, it is time to set up the machine. This will usually necessitate machine tool calibration and mounting the workpiece on the machine. The machine tools used differ depending on the workpiece material and final item design. Precision CNC machining tools are available for a variety of reasons. It is critical to tighten all clamps appropriately and confirm that the machine characteristics, such as coolant levels, are acceptable during this process.
Run the Machine
When the setup is finished, the machine program is ready to run. Most CNC machines include a display for monitoring the program and adjusting various settings. When the program is run, the CNC machine will commence precision CNC machining.
Finishing
The precise machine can remove the part once it has been created. Depending on the needs, the part may be sent for secondary procedures such as grinding or polishing. However, a precision CNC-machined completed product requires no extra processing in most circumstances.
Tolerances in CNC Precision Machining
Although precise CNC machining tools are extremely accurate, they cannot recreate product dimensions exactly as they appear in the CAD blueprint. Machinists use tolerances.
Precision CNC tolerance is not standardized. Tolerance levels vary depending on the production method. The number of decimal places in a tolerance value demonstrates the measurement’s rigor. Here are the various types of tolerance measurement systems:
Limit Tolerances
This occurs when the tolerance value is placed inside a range. For example, if the tolerance of the shaft is 15.5mm and the nominal value is 15mm, this is a limit tolerance.
Unilateral Tolerance Measurement
The deviation is only permitted on one side of the nominal value in this tolerance measurement. This means that if the nominal size of a shaft to go into a bearing is 20mm, a shaft larger than that size will not fit. As a result, machinists only permit deviation on the smaller side of such a shaft.
Bilateral Tolerances
Tolerance of this type allows for a variance on both sides of the nominal value. It is typically represented as a +/- value. To clarify, if a machined item measures 25 mm and has a tolerance of +/- 0.05mm, the value can be between 24.95mm and 25.05mm.
It is essential to understand when to select tighter tolerances for your part-maker. Although tight tolerances are not required for the entire product, critical structural pieces, such as those that fit into other components, require little deviation from the nominal value since inaccuracy can jeopardize the part’s integrity.
Tolerances are significant in precision CNC machining operations because they lower production costs and turnaround times. As vital as they are, they require much expertise and time to get correctly. CNC machines have a typical tolerance of 0.005 inches.
Precision Machining Methods and Equipment
Because of the extensive range of applications, CNC precision machining requires a wide range of machinery and equipment. Here are the machinery and equipment:
Precision Grinders
After machining parts/components, CNC precision machining grinders are one of the final manufacturing operations. Abrasive grinders (or wheels) are used in CNC precision machining grinding to provide a precisely flat surface with a smooth finish on machined objects. By removing little pieces of superfluous material, precision grinding can assist in generating close-tolerance finishes on a finished product.
CNC Turning
The workpiece spins around a central axis in CNC turning while a linearly moving cutting tool removes material from the workpiece. Unlike CNC mills, the cutting tool is normally non-rotary. Single-point cutting tools are most typically utilized in this operation.
CNC Drill Presses
The workpiece is stationary in Computer Numerical Control drill presses, while a rotating drill bit rotates around and drills holes in the workpiece. The holes could be for part assembly or aesthetic purposes. By adjusting the size of the drill bit, CNC drill presses can create a variety of hole sizes. The hole depth can be modified by changing the CNC machine tool calibration.
CNC Milling Machines
CNC milling is a subtractive manufacturing procedure that uses rotary cutters to remove material from an object. Different cutting effects can be achieved by varying the angle, direction, pressure, and cutting tool speed. CNC milling machines have various configurations, including bed, box, planer style, C-frame, gantry, horizontal boring, floor, knee, turret, and ram milling machines.
Electrical Discharge Machining
Electrical discharges (sparks) shape metal in Electrical Discharge Machining (EDM). This procedure is known as spark machining, die sinking, wire erosion, or spark eroding. Because metals carry electricity, electrical discharge machining can only be used on metals.
It employs two electrodes: one for the tool and one for the workpiece. This machining procedure brings The two electrodes close to each other but does not establish physical touch.
An electrical arc forms between the electrodes, boosting the temperature of the part’s electrode and melting the metal. Due to the difficulty of cutting the hardest metals using milling machines, EDM applications typically incorporate them. EDM is frequently used to make holes, slots, and tapers in gears.
Multi-axis CNC Machining
CNC multi-axis machining is a complete machining system. The tool can move in four or more directions. Multi-axis CNC machining allows for the production of complicated parts utilizing various cutting tools and methods, such as milling, waterjet cutting, and laser cutting.
Swiss Machining
Swiss machining is an advancement over traditional CNC lathes. It uses specialist Swiss-made CNC lathes for economical and precise machining of parts. In classic CNC Swiss lathes, the headstock is stationary and merely turns the workpiece. However, with Swiss Machining, the headstock allows for linear movement and more precise and sophisticated machining possibilities.
Mill Turning CNC Centers
CNC mill turning centers, also known as CNC mill-turn machines, combine precision milling and turning processes. Milling and turning have always been done on separate CNC machines. However, combining them into a single CNC machine can considerably simplify the manufacturing process.
CNC mill-turn centers are offered in vertical and horizontal designs. Because of the effect of gravity on the setup, the vertical layout is regarded as more stable. Aside from the moving headstock, a sliding guide bush moves along the workpiece’s longitudinal axis. The guiding bush supports the workpiece during high-precision machining.
CNC Laser Machines
A high-frequency laser beam is used in CNC laser machining to slice or etch materials. Unlike EDM machining, laser machining can machine both metals and non-metals.
CNC Precision Machining Applications
CNC Precision machining is gaining popularity in the manufacturing industry because of its numerous applications, low cost, and quick turnaround times. The method is frequently utilized in a variety of industries, including:
Automotive Industry
Automobile manufacturers must design prototypes of these CNC machined parts before production as innovations are added to their current car revisions. CNC precision machining is in charge of developing these prototypes to exact specifications. The technique also produces components for other modes of transportation, such as shipping vessels, transport trucks, and others.
Medical Industry
Medicine is rapidly evolving, requiring the acquisition of new precision CNC machining equipment. They need large quantities of existing equipment in addition to new ones. Precision CNC machining is in charge of producing this equipment. Examples include orthotic devices, safe enclosures, implants, MRI machines, research equipment, and other such items.
Military and Defense Industry
CNC has never been more important, with various nations developing their ideas for new ammunition and defense systems. All of these ideas are brought to life by the precision machining process, which employs a variety of materials and methods. Examples include plane parts, transportation components, communication components, ammunition, and other items created for this industry.
Aerospace Industry
Aerospace vehicles, from transportation planes to space shuttles, require highly accurate contraptions because a single inaccuracy could seriously harm the various aeronautical vehicles. CNC precision machining produces multiple components in this business, including landing gear ports, bushings, manifolds, airfoils, etc.
Advantages of High Precision CNC Machining
Using these high-precision devices in your production process will undoubtedly bring numerous benefits. High-precision machining is the most cost-effective option, especially if you only need a few to a hundred items. Due to the mold production expenses, the procedure requires a lower upfront cost than injection molding.
Compared to injection molding, CNC machines give a faster rate of speed. In contrast to injection molding, which can take months to create a mold and guarantee the machined parts are within tolerance, CNC machining can deliver items in weeks.
Disadvantages of High Precision CNC Machining
Despite the numerous benefits of CNC precision machining, companies should exercise caution when requiring close tolerances. While CNC precision machining may be required for particular features and dimensions, requiring CNC precision machining when normal machining tolerances would suffice can be a huge waste of resources.
This is because a part with a 0.01 mm tolerance may necessitate a completely different machine configuration than a feature with a 0.05 mm tolerance, significantly boosting labor costs. If your request for quotation (RFQ) yields a higher estimate than expected, consider lowering tolerances for non-critical parameters.
Suitable Materials for Precision Machining
Precision machining can be used on various metals, polymers, and composite materials. Here are some common CNC machining materials for precise machining:
Metals and Alloys
- Brass
- Stainless Steel
- Carbon Steel
- Bronze
- Copper
- Titanium
- Exotic Alloys
- Aluminum
- Steel
- Tool Steel
Plastics and Other Non-metals
- Polycarbonate (PC)
- Acrylonitrile Butadiene Styrene (ABS)
- Graphite
- Polyoxymethylene (POM)
- Glass
- Polymethyl Methacrylate (PMMA)
- Polyamide (PA)
Cost of Precision CNC Machining
There is no definite cost for precision machining because expenses vary depending on various factors. CNC machining has several different components, each with a varied price. For example, the number of axes can be selected in precision machining equipment.
When hourly rates are compared, a multi-axis machine can cost two to three times as much as a three-axis machine. Additional expenditures include the designer’s fee for the Computer Aided Manufacturing (CAM) plan, the hourly labor cost of a precision machinist, and so on.
Conclusion
CNC precision machining is an effective method for producing custom precision machined parts. Aside from generating high-quality components, it also saves money and allows you to get your items to market faster. As a result, a precision CNC machine shop can provide improved part performance and hence boost your company’s bottom line. If you want the greatest results, you should engage with a reputable CNC machine business with an in-house engineering department. AT Machining boasts skilled experts who are well-versed in CNC precision machining procedures. Request a quote today for top-notch CNC precision machining services.
