Eray Cavus 030060022 6th Week

Vibratory Finishing (Manufacturing Method)

Vibratory Finishing (old):

Vibratory finishing was introduced in the late 1950s as an alternative to tumbling. The vibrating vessel subjects all parts to agitation with the abrasive media, as opposed to only the top layer as in barrel finishing. Consequently, processing times for vibratory finishing are significantly reduced. The open tubs used in this method permit inspection of the parts during processing, and noise is reduced.
Most of the media in these operations are abrasive; however, some media per­form nonabrasive finishing operations such as burnishing and surface hardening. The media may be natural or synthetic materials. Natural media include corundum, granite, limestone, and even hardwood. The problem with these materials is that they are generally softer (and therefore wear more rapidly) and nonuniform in size (and sometimes clog in the workparts). Synthetic media can be made with greater consistency, both in size and hardness. These materials include AI2O3 and SIC, compacted into a desired shape and size using a bonding material such as a polyester resin.
(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.664)

Vibratory Finishing(new) : (better)

Vibratory finishing is particularly effective for deburring, forming radii, descaling, and removing flash from castings and molded parts. It may also be used for burnishing. Vibratory finishers deburr parts 50 to 75% faster and are more versatile than rotary tumbling barrels. There is no caseading of parts, with the attendant possibility of damage by impact. The process is adaptable to both light castings and formed parts. Vibratory finishing is also effective on internal suraces and recesses that are not usually worked by rotary tumbling.

(Copper and copper alloys, Yazar: Joseph R. Davis,page:323)

Cotter Pins (Fixing tool)

Cotter Pins(old)

Cotter pins are fasteners formed from half round wire into a single two-stem pin.They vary in diameter ,ranging between 0.8 mm and 19 mm ,and in point style.Cotter pins are inserted into holes in the mating parts and their legs are split to lock the assembly.They are used to secure parts onto shafts and similar application.

(Fundamentals of modern manufacturing,materials,processes and systems,3rd edition, Mikell P.Groover, p.775) 01.00

Cotter Pins(new) (better)

In garages, where it is necessary to extract and spread cotter pins frequently, the special tool for this purpose shown in the drawing will be found of considerable utility. An old pair of pliers is forged and filed to the shape shown in the illustration, then hardened and tempered. A lip on one jaw opens the cotter pin and spreads it, while the notch in the other jaw prevents the head of the pin from slipping. The ends of the jaws are ground down to fit under the head of the cotter pin to extract it, as shown in the lower drawing. The jaw ends should be rounded, to prevent cutting the pin.

(Popular Mechanics Magazine,page:792)

Blast Finishing (Manufacturing Method)

Blast Finishing (old)

Blast finishing uses the high-velocity impact of particulate media to clean and finish a surface. The most well known of these methods is sand blasting, which uses grits of sand (S1O2) as the blasting media. Various other media are also used in blast finishing, including hard abrasives such as aluminum oxide {AI2O3) and silicon carbide (SiC), and soft media such as nylon beads and crushed nut shells. The media is propelled at the target surface by pressurized air or centrifugal force. In some applications, the process is performed wet, in which fine particles in a water slurry are directed under hydraulic pressure at the surface.
(Mikell P. Groover,Fundamentals of Modern Manufacturing,4th Edition,pg.663)

Blast Finishing (new) (better)

The removal of flash from molded objects (and/or dulling their surfaces) by impinging media such as steel balls, crushed apricot pits, walnut shells or plastic pellets upon them with sufficient force to fracture the flash. When the material being deflashed is not sufficiently brittle at room temperature, the articles are first chilled to a temperature below their brittleness temperature. Typical blast-finishing machines consist of wheels rotating at high speeds, fed at their centers with the media, which are thrown out at high velocities against the objects.

(Encyclopedic Dictionary of Polymers, 1. Cilt, Yazar: Jan W. Gooch, page:84)

 

Plunge Milling (Manufacturing Method)

Plunge Milling (old) (better)

This is a high-performance roughing technique in which a milling tool is moved multiple times in succession in the direction of its tool axis or of its tool vector into the material area that is to be removed, forming plunge-milling bores. The bores are superposed to eliminate the material of a pocket or zone. This technique is also referred to as milling in the Z-axis; it is more efficient than conventional endmilling for pocketing and slotting difficult-to-machine materials and applications with long overhangs. The machining parameters depend on the insert size, the tool overhang and the tool diameter. When a tool overhang of ∅ 6 mm is used, the usual step between two bores must be lower than 0.75 ∅. The radial depth of cut is 1 mm less than the radial length of the insert edge. If overhang increases the step must be reduced.
The advantages of the plunge-milling technique are:
• reduction by half in the time needed to remove large volumes of material;
• reduced part distortion;
• lower radial stress on the milling machine, meaning spindles with worn bearings can be used to plunge mill;
• long reach, which is useful for milling deep pockets or deep side walls.
Plunge milling is recommended for jobs such as roughing cavities in moulds and dies. It is recommended for aerospace applications, especially in titanium and nickel alloys. Inserts specifically for plunging are available for roughing and semi-finishing, but inserts suitable for high-feed milling can be also used for this technique.

(Machining of Hard Materials, J. Paulo Davim; Page:78-79)

Plunge Milling (new)

A plunge milling tool-path is obtained by making the cutter carry out several axial plunging trajectories(Fig. 4.4). Material is removed during the plunging phase. Plunge milling parameterization consists in determining the plunging points and the manner how the cutter goes from one to another. In contrast with usual radial tool-paths such as direction parallel and contour parallel which repeat one pattern at several levels, two pattern defines the cutter motions at each plunging point. The guide curve defines the path between the plunging points.

(Machining of Complex Sculptured Surfaces, Yazar: J. Paulo Davim, page:131) 

Trochoidal Milling (Manufacturing Method)

Trochoidal Milling (old) (better)

A trochoidal toolpath is defined as the combination of a uniform circular motion with a uniform linear motion, i.e., toolpath is a kinematics curve so-called trochoid. Light engagement conditions and high-speed milling are applied, in addition to large axial depth of cut. In this way a large radial width of cut is avoided. Slots wider than the cutting diameter of the tool can be machined, all with the same endmilling tool, usually an integral one. Since a small radial depth of cut is used, cutters with close pitch can be applied, leading to higher feed speed and cutting speed than with ordinary slot-milling applications. A main drawback is that toolpath length is much higher compared to standard toolpaths such as zigzag because large tool movements are without engagement into the material. Moreover, in the case of sculptured surfaces, overlarge steps are produced on the surface, making very difficult the following semi-finishing operation. Therefore it is recommended for slotted shapes but not for free-form machining. Currently all commercial computer-aided manufacturing (CAM) packages allow easy programming of this method.

(Machining of Hard Materials, J. Paulo Davim; Page:81-82)

Trochoidal Milling (new)

Trochoidal milling tool-paths are 3-axis milling strategies mostly dedicated to roughing operations. The tool-path is defined as the combination of a uniform circular motion with a uniform linear motion.

As for plunge milling, trochoidal milling parameters can be sorted into two groups: trochoidal pattern parameters (trochoidal radius, tool radius and trochoidal step) which determine how material is removed and guide curve parameters which are linked to feature geometry. One great interest of trochoidal paths is consequently that process requirements (such as tool loads or chip thickness) are independent from the feature geometry.

(Machining of Complex Sculptured Surfaces, J. P. Davim, page:4-9)