Precision Machining: How to Recognise an Expert

A Digital Micrometer: measures 0 to 25mm with 0.001mm resolution

Precision machining is the process of taking a raw material and shaping or changing it in some way using a material removal procedure. It is also often referred to as precision engineering.

There are many varied techniques, and types of machines, used to manufacture high volumes of identical parts.

Precision machining is commonly undertaken by CNC (Computer Numerical Control) Machines. These are programmed to follow a sequence of steps, which contributes to their excellent accuracy and precision.

Objects, such as machines and tools, often need to be preceded by complex diagrams that are done in three dimensions. The designs must be strictly followed to machine a quality product with integrity.

A skilled and experienced machinist will ensure that your parts are made fit-for-purpose. You want exactly the same high-quality part manufactured each time.

Why Precision Machining is Important

Precision machining is particularly important to create tools and parts in a way that is precise, stable, and can be repeated with consistency, accuracy, and durability.

Precision machining is used in many industries to design and create products. Most machinery-based industries use precision machined components during their manufacturing processes.

Almost all the major industries make use of precision machining in one way or the other. Industries with high-level sophistication and low-level tolerance are most dependent on precision machining.

CNC Machines can be quickly and easily adapted to different materials, even using the same machines. A range of materials can be precision machined, including polymers, plastic, aluminium, steel and stainless steel, bronze, copper and titanium.

Tolerances and Precision Machining

Precision machining can be used to create a wide variety of products, items, and parts for any number of different objects and materials. These parts usually require tight tolerances variation from nominal dimensions and from part to part. This means that there is not much room for error in the production of the component.

Repeatability and well-controlled tolerances are hallmarks of precision machining.

If two parts are to be joined together a decision is taken as to how close a fit is required. This is where you can seek help from your machinist.

CNC machines produce very accurate components, and they do so repeatedly for two or even 2,000 pieces.

Tolerances between 25 to 50 microns are relatively easy to achieve. Tolerances of less than 25 microns are more challenging, yet many companies regularly hold even tighter tolerances between 5 to 12 microns.

Machining Expertise

An experienced CNC machinist concentrates on: automated manufacturing, quality control, precision manufacturing, development of tools, customer satisfaction, and on optimising processes.

Search for CNC machining companies that are ISO 9001: 2015 certified and can demonstrate a history of successful precision machining. Your machinist must be able to suggest design improvements, translate 2D and 3D drawings into G-code for programming CNC machines (see below) and advise on material choice.

Your precision machinist will have in-house drafting services to assist with quality and specifics.

The Machines

The most three common CNC machines used in precision machining include:

1. CNC Milling Machines

Milling is a process that is quite similar to drilling or cutting, and milling can perform these processes for a variety of production needs. Milling utilises a cylindrical cutting tool that can rotate in various directions.

The CNC milling machine can be programmed to vary in depth, angle and direction of cut. A 3-axis machine operates along both the X and Y horizontal axes, as well as the Z vertical axis. A 4-axis machine includes a rotary dimension to its linear capability, which allows it to cut along an arc.

2. CNC Lathes

Lathes used in turning centres operate by rotating the material rapidly on a spindle. While the material is turning, using a single point tool mounted on the lathe’s axis, it performs processes like threading, knurling, facing, turning or sanding.

CNC lathes are ideal for manufacturing symmetrical objects that have conical, spherical or cylindrical shapes.

3. CNC Drilling Machines

Sophisticated drilling machines can be programmed using CNC technology to ensure precise positioning of holes in materials. With thick material, a process called peck, or interrupted cut drilling is used to drill the hole in a stepwise procedure.

CNC turret drilling machines have several drill bits and cutting tools mounted on a turret. Automation enables the required tool to be indexed quickly and accurately into position for drilling.

To conclude, precision machining is critical for the manufacturing of high-tolerance, repeatable parts. So, when sourcing a precision machining supplier do enquire as to how tolerances are to be achieved, the best material to use, steps in the machining process, and how a high level of quality is maintained over a volume run.

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