Machine Shop Services Selection GuideMachine Shop Services Selection GuideMachine Shop Services Selection Guide

Image Credit: Drill String Services, Inc. | IMR Test Labs | Westmoreland Mechanical

 

Machine shop services consist of any of a number of tasks performed in machine shops. They can provide services for parts in quantities ranging anywhere from prototype through high production. Other names for machine shops are tool rooms or job shops.

 

CNC Machine In Operation. Video Credit: Youtube - CapriMikeC user

 

Using Machine Shop Services

Machine shop services are contracted by manufacturers who do not have the ability to handle the work internally due to skill, capacity, or budget constraints. Typically detailed part design drawings are submitted to the machine shop. The shop then buys the material, manufactures the part(s), and returns the finished part(s) to the manufacturer. Some machine shops will sub-contract work that they cannot do effectively, such as heat treating and plating.

 

Shop Capabilities

The first priority in selecting a machine shop is finding one with the capabilities to perform the needed service.

 

Types of Machining

The chart below provides a list of various types of machining operations performed by machine shops along with a summary of what each involves.

 

Machining Operation

Summary

Boring

 

Process involving the enlarging of existing holes in a workpiece.

 

Deep Hole Drilling

Several different processes can achieve deep-hole drilling. Trepanning cuts a narrow grooved surface in to a workpiece. Gun drilling is a quick and efficient method of producing deep or shallow close tolerance holes with smooth surface finishes - usually in one pass. The boring process uses a lathe, boring machine, or boring mill to make or enlarge a cylindrical hole.

 

Jig Boring

Jig boring is a precision machining process that includes centering, drilling, reaming, counter boring, contouring, through-boring and step boring. Jig boring machines are similar to jig grinders, but use boring tools instead of high-speed grinding wheels.

Milling

 

Milling machines are versatile devices that can perform many different cutting, shaping, boring, and forming operations.

 

Broaching

Broaching is a specific type of milling involving a toothed cutting tool for precision machining of odd shapes like holes, splines, and keyways. Broaching can be used to enlarge, shape, or smooth a bored or drilled hole, and to remove material between two adjacent drilled holes. For example, a round hole can be broached to a square or other shape.

 

Drilling

The drilling process produces cylindrical holes of various sizes into parts.

Lathe Machining

 

Machining processes involving the use of a lathe, used to shape and cut cylindrical parts.

 

Turning

Turning is performed on a lathe, used to reduce the diameter of a part to a desired dimension.

 

Screw Machining

Screw machining is a high volume turning process used for the rapid and accurate production of parts from a variety of materials.

 

Swiss Machining

Swiss screw machining is another high volume turning process used for the close-tolerance production of very small parts.

Abrasive Machining

 

Machining processes involving the use of abrasive materials to polish, cut, and form parts.

 

Abrasive Flow

Abrasive flow machining (AFM) uses a mixture of abrasive grain in a high-viscosity carrier media to deburr, polish and generate controlled-radius geometry in components.

Orbital AFM processes are used for external finishing and geometry control. Micro-AFM processes are used to radius, deburr and improve the surface finish of orifices in nozzles, fuel injectors, spray tips or other parts with very small or micro-sized holes.

 

Abrasive Jet

In abrasive jet machining, the cutting action is done by a high velocity stream of abrasive filled water or gas. The result is a very small width cut, allowing for precise machining heat sensitive, brittle, thin, or hard materials.

 

Honing

Honing uses abrasive stones or silicon-carbide slips to obtain a specified finish or dimensional tolerance on the surface of a workpiece through a scrubbing action.

Grinding

 

Process that uses an abrasive grinding stone or wheel to remove material from a workpiece, typically for polishing or cutting/shaping of harder materials.

 

Centerless Grinding

Centerless grinding is a machining operation which does not require a center hole, driver, or workhead fixture. It is used to grind and finish parts without mechanically constraining the workpiece for stability.

 

Creep Feed Grinding

Creep feed grinding is a type of plunge grinding that uses specialized grinding equipment to remove material at higher rates than a typical grinding process.

 

Double-disc Grinding

Disc grinding is used to produce flat, parallel parts in high-volume production. Most disc grinding machines have two independent grinding wheels and are called double-disc grinders.

 

ID / Internal Grinding

Internal grinding or ID grinding uses a small, high-speed grinding wheel and is used to grind the inner diameter (ID) of holes or surfaces.

 

OD / External Grinding

External grinding or outer diameter (OD) grinding is used to grind the external or outside surfaces of cylindrical parts.

 

Jig Grinding

Jig grinding uses very precise machines for locating and generating very accurate holes, contours, and surfaces to tolerances of .0001" or less. Jig grinders are similar to jig borers, but use high-speed spindles and grinding wheels instead of boring tools.

 

Surface Grinding

Surface grinders are used to produce flat and parallel surfaces. The work is mounted to a table and fed back and forth under the grinding wheel.

Electrical Discharge Machining (EDM)

 

Low-volume process that uses electrical discharges (sparks) to machine parts, providing the ability to create complex shapes at extremely close tolerances.

 

Electrode EDM

Electrode EDM is a type of electric discharge machine (EDM) that uses a shaped die sinker or electrode to cut complex shapes with odd angles.

 

Wire EDM

Wire EDM is a type of electric discharge machine (EDM) that uses a wire to cut parts. Wire EDM is typically used to cut plates up to 300mm thick and to make tools and dies from hard metals.

Laser Machining

 

Laser machining is a material removal process accomplished by laser / material interaction. It is used to create precise cuts with easier workholding and reduced contamination (no solid cutting edge).

Etching / Chemical Milling

 

Process involving the use of strong acid or other chemicals to cut into unprotected parts of material. Electrochemical reaction removes material and creates a recessed image or design. It is used commonly for PCB and semiconductor manufacturing and for metal and glass designs.

 

Electrochemical / Photochemical Machining

Electrochemical machining and photochemical machining is used to etch or create unstressed, high-precision parts. It is a high volume process typically used for extremely hard or difficult materials.

 

Secondary Treatment

Some machine shops may have the capabilities to treat the finished parts after machining. Some of these treatment operations include:

  • Anodizing - Anodizing is a galvanic finishing process well suited to aluminum and its alloys.  Anodized finishes can be hard for wear applications, or can include corrosion-resistant properties or a wide variety of colors.
  • Black Oxide Application - Black oxide is applied as an anti-corrosion treatment for a variety of steels.
  • Electroplating - Electroplating is a finishing process often used for materials such as brass, bronze, and copper.  A wide variety of colors and textures can be achieved.
  • Heat Treating / Stress Relieving - Heat treating is a broad category of processes used to treat metals (e.g., annealing, passivation, hardening, etc.). Stress relieving is used to relieve residual stresses imposed during the stamping process.
  • Lapping / Polishing - Lapping and polishing processes use abrasive materials to smooth, polish, and brighten surfaces.
  • Painting / Powder Coating - Painting and powder coating apply decorative and/or protective finishes. Typically, coatings are thicker than plating or anodizing operations.
  • Welding - Welding joins parts by melting and reforming a bond between materials, with or without additional filler metal.

Specialty Machining

Some machine shops may provide specialty services for a particular application or with a particular type of technology.

 

Specialty applications include:

  • Casting machining - grinding of cast parts
  • Forging machining - grinding of forged parts
  • Extrusion machining - machining of extruded parts
  • Gear manufacturing - production of gears
  • Jigs and fixtures - jig and fixture design and machining
  • Tool & die manufacturing - machining of tools and dies

Specific technologies include:

  • CNC Machining - CNC (Computer Numeric Controlled) machines are used in most machine shops for high volume work. They are programmable, computer-controlled machines that can make fast and repeatable actions, creating parts quickly and efficiently. CNC software also allows CAD drawings to be uploaded and used directly for part production. For more information on CNC machining, visit the CNC Machining Services Selection Guide on GlobalSpec.

Machine Shop Services Selection Guide

CNC lathes and machining centers can cut materials on many axes. Image Credit: Kollewin

  • Micro machining - Micro machining involves precision machining of of very small parts. 

Machine Shop Services Selection Guide

Image Credit: SCHUNK Inc.

 

Serviced Materials

Machine shops typically list what types of materials they can work with based on what their equipment is designed to handle. The desired part material will thus need to be considered when selecting an appropriate machine shop service. Different types of serviced materials include:

  • Metals & Alloys (e.g. Aluminum, Brass, Steel, etc.)
  • Ultra-hard Materials & Hardened Metals
  • Plastics
  • Ceramics
  • Glass
  • Rubber
  • Stone, Marble, & Granite
  • Wood

Standards

ISO 9000:2008 is the current standard that machine shops work towards. It is a global standard that applies to all types of organizations in regards to effectiveness of their quality management system (QMS). Customers should consider ISO 9001, which deals with the requirements that an organization must fulfill in order to meet the standard. The standard helps to provide assurances that a machine shop will produce good quality parts on time.

 

Other Considerations

Once all of the service criteria for part production have been met, factors such as cost and location need to be added to the equation.

 

Cost

The cost of a service is important to consider in any application. Quotes (cost estimates) for orders or services are given to the customer after he or she provides the supplier with a description of the job requirements. Cost typically correlates to the time spent producing the product and the expense of the materials used (when purchased by the service company). Additional costs include transportation or shipment costs of the parts once they have been made.

 

Location

The location of the service provider is important to consider both for logistical reasons and expenses. Operations located farther away from the customer will have higher associated shipping costs. In addition, there may be additional logistical complications when dealing with suppliers from different countries.


Related Products & Services

  • Centerless Grinding Services

    Centerless grinding services perform a machining operation in which an abrasive wheel grinds metal from a bar surface while a regulating wheel forces the bar against the grinding wheel.

  • CNC Machining Services

    CNC machining services use fast, repeatable, and programmable machines which can function while unattended in order to manufacture parts quickly and efficiently.

  • EDM Machining Services

    EDM machining services remove metal by burning instead of cutting or grinding. There are three basic types of electro discharge machining (EDM) operations: electrode EDM, wire EDM, and small-hole EDM.

  • Lapping Services

    Lapping services uses a free abrasive machining process, which produces finished components without introducing stresses and heat damage associated with other processes.

  • Laser Machining Services

    Laser machining services use computer-controlled lasers to perform a variety of material removal processes. These lasers can be positioned and controlled with a high degree of accuracy, allowing for a variety of effects to be achieved.

  • Plastic Machining Services

    Plastic machining services fashion or fabricate parts and components out of various plastic and thermoplastic materials.

  • Waterjet and Abrasive Jet Cutting Services

    Waterjet and abrasive jet cutting services use high-pressure media to cut materials.