Previous One
Chip breakers are important element of tool design. Ductile materials such as low carbon steel, copper, aluminium, zinc, brass, etc. when, produce long continuous ships which are difficult to handle and dispose of as they occupy large volumes. The chip breaking and chip curl have assumed great importance.Chip breakers are obstacles provided in the cutting tools which reduce the swarf into small pieces as they are formed. The metal plastically deformed during cutting resulting in work hardening. The chip breaker performs effectively with work hardened material. There are basically two types of chip breakers.(i) Groove type(ii)Obstruction type
(Singal R.K., Singal M., Singal R., Fundamentals of Machining and Machine Tools, 2008, pg.101)
(Singal R.K., Singal M., Singal R., Fundamentals of Machining and Machine Tools, 2008, pg.101)
New One
The controlling and breaking of chips are essential in machining operation due to its significance with reference to personal safety, possible damage to equipment and product, handling and disposal of swarf after machining, cutting forces, temperature and tool life.
Chip breaker refer to a modification of the tool face to control or break the chip, consisting of either an integral groove or an integral or attached obstruction. Chip curvature is an important factor in this context and the chip curl may be increased by the use of chip breaker.
However it should be noted that in addition to the design of a good chip breaker. It is necessary to have a correct tool geometry enabling the chip to follow proper path across the tool face.
Types of chip breakers;
1- Integral Obstruction Type Chip Breaker
2- Attached Obstruction Type Chip Breaker
3- Groove Type Chip Breaker
(Kuppuswamy G., Principles of Metal Cutting , 2008, pg.161 - 163)
2-) Dyad by Dyad Approach
Previous One
A dyad by dyad approach means that pairs of organizations jointly develop the new processes and MPC systems that allow them to ever more effectively integrate their detailed operations. It is dyad by dyad because the joint working and definitions of improvement projects will tend to be unique to the dyad. This said, best practice will be able to learn as mush as possible from each dyad improvement effort, and then imbed the MPC thinking, processes, and systems int modular approaches to whatever extent possible. That is, one should work hardest with smart partners where new chain benefits are achived, but then try to leverage the learning in other dyads."
(Manufacturing Planning and Control For Supply Chain Management, T. E. Vollmann, page# 665)
New One
Vollman highlight the problematic nature of subcontract manufacture management in the dyad-by-dyad approach. They focus on what they see as the next major area for definitively different MPC3 development on a dyad-by-dyad approach. The dyad-by-dyad approach means that pairs of organizations jointly develop the new processes and MPC systems that allow them to ever more effectively integrate their detailed operations. They see that state-of-the art improvements in supply chains are achieved by working in dyads – pairs of companies that commit to joint new ways of working, new processes, and new MPC systems. They continue by saying that there are people today, who see supply chain management as an extension of ERP4, achieved by connecting ERP systems between companies. This is not going to be sufficient. The frontier is to integrate between firms. This requires new thinking – and new transformation (work, processes, and MPC systems). Suboptimal working such as ordering, extensive transaction processing, duplicate inventories, and multiple quality checks are being eliminated. In dyads, new processes are being established, and new information systems support these processes. But there are not yet standard processes and systems available for all to implement.
(Hakkinen K., Managerial approach to subcontract manufacture co-operation in the metal industry, pg.13)
3-) Implosion
Previous One
The pressure differance (0,1MPA) between inside of the vacuum enclosure and outside initiate an accidental implosion of an evacuated birttle containeer, resulting in flying fragments. Glass and perspex viewports represen an implosion hazard.
R. Hellborg, Electrostatic accelerators: fundamentals and applications, P.366
R. Hellborg, Electrostatic accelerators: fundamentals and applications, P.366
New One
Explosion and Implosion are the core processes of CPE which either move work units forward (implosion) to project completed parts or backwards (explosion) to determine starts required across the BOM (bill of materials) supply chain following the appropriate manufacturing data such as cycle time, yield, capacity and product structure. We typically use implosion to estimate what finished goods will be available to meet demand and explosion to estimate what starts are needed at what due dates to ensure meeting the existing demand on time.
(Kempf G.K., Planning Production and Inventories in the Extended Enterprise: A State of the Art Handbook, vol.2, pg.331)
4-) Broaching Machines
Previous One
A broaching machine typically consist of a workholding device, a drive mechanism, and a supporting frame. Shown is a vertical push down machine. The broaching tool is pushed through or across the workpiece, which is held stationary. Other types of broaching machines include pull broach, surface broach, and continuous broach. These broaching machines are either horizontal or vertical. Most machines are hydraulically powered, but some are driven electromechanically.
( Manufacturing process reference guide - Robert H. Todd, Dell K. Allen, Leon Alting - page 16 )
New One
Broaching is a metal removing process by a cutting tool called broach. It is faster and cheaper method of machining. It is used to machine keys, splines, square, rectangular and polygon holes, serration internal gears, etc..
Principle Of Operation
The work piece is set on the table by means of fixture. The broach is moved over the surface in a fixed path. the broach has multiple cutting teeth along its length. The height of tooth is gradually increasing. Each tooth removes a very small amount of metal.
Types of Broaching Machines:
- According to the direction of the cutter: 1- Horizontal 2- Vertical
- According to the method of cutting: 1- Pull type 2- Push Type 3- Continious Type
- According to the type of drive: 1- Mechanical drive 2- Hydraulic Drive
(Kesevan R. Ramanath V.B., Manufacturing Technology - II, 8.1-3)
5-) Overcut ( In EDM)
Previous One
Overcut in Edm is due to side sparks and is dependent on the gap length and crater dimensions. Lazerenko has shown experimentally that overcut O can be expressed by the relationship O= A(C) ^ (1/3 ) + B where A and B are constants, the values of which depend upon the tool work pair. Dependence of the overcut on the capacitance C is shown in Fig. 4-30
( Modern machining process - P.C. Pandey, H.S. Shan - page 110 )
New One
Overcut means the difference between the size of the electrode and the size of the cavity created during machining. There is a possibility of taper cut and overcut in EDM, they can be controlled and compensated. Product quality is a very important characteristic of a manufacturing process along with MRR. The followings are the product quality issues in EDM.
• Surface finish
• Overcut
• Tapercut
No two sparks take place side by side. They occur completely randomly so that over time one gets uniform average material removal over the whole tool cross section. In EDM, the spark occurs between the two nearest point on the tool and workpiece. Thus machining may occur on the side surface as well leading to overcut and tapercut. Taper cut can be prevented by suitable insulation of the tool. Overcut cannot be prevented as it is inherent to the EDM process. But the tool design can be done in such a way so that same gets compensated.
(Krar S.F., Oswald W.J., Amand St.E.J., Technology of Machine Tools, Page:630)
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