Way (machine tool element)

Last updated

A way (sometimes known as a slideway, guideway, or bedway) is a type of linear bearing, specifically a linear plain bearing, in a machine tool. It facilitates precise linear motion along a given axis. A way is ground, scraped, or (less often) molded to be very flat, and ways often come in pairs to ensure a flat plane for the carriage or sliding element (slide) to move along smoothly. Ways are usually lubricated with way oil (a kind of machine oil specially made to adhere to the ways while vertical). [1]

Contents

Ways have been used since the 19th century and are a critical part of manufacturing processes, especially those requiring low tolerances such as machining. They have been made of various materials over the years, ranging from wood to cast iron, and nowadays including plastic alloys and special polymer materials. They are crafted with painstaking precision, usually being scraped into near total flatness with hand tools. This flatness is required to both provide good results in the manufactured parts, as well as prevent the stick-slip phenomenon (jerking motion due to friction at low speeds). In recent years they have started to be phased out by rolling-element bearings ("ball" bearings), or are forgone entirely in some CNC machines. [1]

Materials

The material the way is made from has differed and evolved since their invention.

Though ways have also been made from wood, the most common material for ways is cast iron, which provides a rigid and durable base for the ways to be formed on. Ways made from cast iron usually have to be scraped into the final dimensions by hand, which is a long and laborious process. [2]

In the late 20th century, composite materials have started to come into use, such as the plastics Turcite and Rulon. These materials are applied to the ways in strips with adhesive, acting as a sacrificial surface that wears instead of the iron, while keeping the same degree of flatness. The composite materials help to reduce friction between the way and the slide, further reducing maintenance costs and downtime. [3] [4]

Geometry

The geometry of the way can vary depending on the situation. The most common types are flat, vee, and dovetail ways.

Flat ways are used when there is little requirement for the slide to be constrained perpendicular to the axis of movement, or the constraint is being provided by another component or otherwise not needed, such as on the carriage of a lathe.

Vee (V-shaped) ways provide constraint to the perpendicular horizontal axis, but do little to prevent the slide from being lifted vertically.

Dovetail ways provide constraint in both perpendicular axes, and are usually used when the slide is lifted vertically along the ways and must be prevented from falling off. This type usually has an adjustable tightness to the way using a gib-strip (a metal piece placed on one side of a dovetail to tighten the fit). [1]

The precise and accurate geometry of the ways (that is, their shape, size, and flatness) is produced via any combination of milling (for roughing and semifinishing), grinding (for any stage up through finishing), lapping (in some cases, for final finishing), or hand scraping (in many cases but not all), with comparison against surface plates as reference standards for the flatness, as well as any other similar reference standards (e.g., precision cylindrical standards or rings) if concave or convex cylindrical ways are needed.

Features

The ways are often fitted with additional features to decrease wear and ease maintenance.

The way is lubricated with way oil, which is specially formulated to reduce friction, but has an additive that makes it adhere to the ways, even vertically. The oil is applied to the ways with either grease fittings, or is sometimes continuously pumped through ducts machined into the face of the ways. The latter was commonly used on shapers, where the entire way is covered by some part of the sliding element at all times. The ends of the ways are fitted with felt wipers to prevent oil from leaking out as the slide overhangs the ways.

Protective guards are sometimes fitted to prevent metal shavings or dropped objects from damaging the ways. [1]

See also

Related Research Articles

<span class="mw-page-title-main">Piston</span> Machine component used to compress or contain expanding fluids in a cylinder

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.

<span class="mw-page-title-main">Lathe</span> Machine tool which rotates the work piece on its axis

A lathe is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, threading and turning, with tools that are applied to the workpiece to create an object with symmetry about that axis.

<span class="mw-page-title-main">Machine tool</span> Machine for handling or machining metal or other rigid materials

A machine tool is a machine for handling or machining metal or other rigid materials, usually by cutting, boring, grinding, shearing, or other forms of deformations. Machine tools employ some sort of tool that does the cutting or shaping. All machine tools have some means of constraining the workpiece and provide a guided movement of the parts of the machine. Thus, the relative movement between the workpiece and the cutting tool is controlled or constrained by the machine to at least some extent, rather than being entirely "offhand" or "freehand". It is a power-driven metal cutting machine which assists in managing the needed relative motion between cutting tool and the job that changes the size and shape of the job material.

<span class="mw-page-title-main">Ball bearing</span> Type of rolling-element bearing

A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.

Fluid bearings are bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces. Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings. Thus, it is possible for some fluid bearings to have near-zero wear if operated correctly.

<span class="mw-page-title-main">Bearing (mechanical)</span> Mechanism to constrain relative movement to the desired motion and reduce friction

A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Most bearings facilitate the desired motion by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or the directions of the loads (forces) applied to the parts.

<span class="mw-page-title-main">Cutting fluid</span> Coolants and lubricants used in metalworking

Cutting fluid is a type of coolant and lubricant designed specifically for metalworking processes, such as machining and stamping. There are various kinds of cutting fluids, which include oils, oil-water emulsions, pastes, gels, aerosols (mists), and air or other gases. Cutting fluids are made from petroleum distillates, animal fats, plant oils, water and air, or other raw ingredients. Depending on context and on which type of cutting fluid is being considered, it may be referred to as cutting fluid, cutting oil, cutting compound, coolant, or lubricant.

<span class="mw-page-title-main">Shaper</span> Machine tool which linearly cuts or grinds the workpiece

In machining, a shaper is a type of machine tool that uses linear relative motion between the workpiece and a single-point cutting tool to machine a linear toolpath. Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical.

<span class="mw-page-title-main">Plain bearing</span> Simplest type of bearing, with no rolling elements

A plain bearing, or more commonly sliding contact bearing and slide bearing, is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore, the part of the shaft in contact with the bearing slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe.

<span class="mw-page-title-main">Rolling-element bearing</span> Bearing which carries a load with rolling elements placed between two grooved rings

In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements between two concentric, grooved rings called races. The relative motion of the races causes the rolling elements to roll with very little rolling resistance and with little sliding.

<span class="mw-page-title-main">Drilling</span> Cutting process that uses a drill bit to cut a circular hole into the workpiece

Drilling is a cutting process where a drill bit is spun to cut a hole of circular cross-section in solid materials. The drill bit is usually a rotary cutting tool, often multi-point. The bit is pressed against the work-piece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the work-piece, cutting off chips (swarf) from the hole as it is drilled.

<span class="mw-page-title-main">Rolling</span> Type of motion which combines translation and rotation with respect to a surface

Rolling is a type of motion that combines rotation and translation of that object with respect to a surface, such that, if ideal conditions exist, the two are in contact with each other without sliding.

<span class="mw-page-title-main">Pillow block bearing</span> Bracket used to provide support to rotating shafts

A pillow block bearing is a pedestal used to support a rotating shaft with the help of compatible bearings and various accessories. The assembly consists of a mounting block which houses a bearing. The block is mounted to a foundation, and a shaft is inserted, allowing the inner part of the bearing/shaft to rotate. The inside of the bearing is typically 0.025 millimetres (0.001 in) larger diameter than the shaft to ensure a tight fit. Set screws, locking collars, or set collars are commonly used to secure the shaft. Housing material for a pillow block is typically made of cast iron or cast steel.

<span class="mw-page-title-main">Hand scraper</span>

A hand scraper is a single-edged tool used to scrape metal or other materials from a surface. This may be required where a surface needs to be trued, corrected for fit to a mating part, needs to retain oil, or to give a decorative finish.

<span class="mw-page-title-main">Metal lathe</span> Machine tool used to remove material from a rotating workpiece

In machining, a metal lathe or metalworking lathe is a large class of lathes designed for precisely machining relatively hard materials. They were originally designed to machine metals; however, with the advent of plastics and other materials, and with their inherent versatility, they are used in a wide range of applications, and a broad range of materials. In machining jargon, where the larger context is already understood, they are usually simply called lathes, or else referred to by more-specific subtype names. These rigid machine tools remove material from a rotating workpiece via the movements of various cutting tools, such as tool bits and drill bits.

<span class="mw-page-title-main">Piston ring</span> Part of a reciprocating engine

A piston ring is a metallic split ring that is attached to the outer diameter of a piston in an internal combustion engine or steam engine.

A linear-motion bearing or linear slide is a bearing designed to provide free motion in one direction. There are many different types of linear motion bearings.

<span class="mw-page-title-main">Grease fitting</span> Metal fitting used in mechanical systems to feed lubricants

A grease fitting, grease nipple, Zerk fitting, grease zerk, or Alemite fitting is a metal fitting used in mechanical systems to feed lubricants, usually lubricating grease, into a bearing under moderate to high pressure using a grease gun.

<span class="mw-page-title-main">Yaw bearing</span>

The yaw bearing is the most crucial and cost intensive component of a yaw system found on modern horizontal axis wind turbines. The yaw bearing must cope with enormous static and dynamic loads and moments during the wind turbine operation, and provide smooth rotation characteristics for the orientation of the nacelle under all weather conditions. It has also to be corrosion and wear resistant and extremely long lasting. It should last for the service life of the wind turbine) while being cost effective.

<span class="mw-page-title-main">Milling (machining)</span> Removal of material from a workpiece using rotating tools

Milling is the process of machining using rotary cutters to remove material by advancing a cutter into a workpiece. This may be done by varying directions on one or several axes, cutter head speed, and pressure. Milling covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes for machining custom parts to precise tolerances.

References

  1. 1 2 3 4 Principles of engineering manufacture. Black, Stewart C., 1930- (3rd ed.). Oxford: Butterworth Heinemann. 1996. ISBN   978-0-08-053961-4. OCLC   191823312.{{cite book}}: CS1 maint: others (link)
  2. ↑ USpatent 2675276,Daugherty, Jesse,"SLIDING WAY FOR MACHINE TOOLS AND METHOD OF MAKING SAME",published 1951-09-24,issued 1954-04-13, assigned to Giddings & Lewis Machine Tool Company
  3. ↑ USpatent 2931684,W. Johnson III, Earle,"MACHINE TOOL WAYS",published 1960-04-05,issued 1960-04-05, assigned to Rockford Machine Tool Co.
  4. ↑ Devitt, Andrew (2001). "Straight Talk on Ways". www.moglice.com. Devitt Machinery Company. Archived from the original on 2020-02-21. Retrieved 2020-10-22.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.