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Planishing

Planishing is a kind of work refinement which, when carried to its ultimate state, can render a surface as fine as a mirror. After the raising operation, the work is begun by coarse hammer blows at the rate of about forty percent coverage. During this phase of the work,the most likely fitting stakes are sought out.

In these way the workpiece is not totally committed to stakes that may look right at the outset but later may not fit at all. When the project is important enough, it is fitting that the craftsman make new stakes to fit the needs of the job.

After the first planishing, the piece is annealed and left white, or matte from the pickling. This will help in seeing the new hammer marks better. This time the coverage is increased to sixty percent, not counting the previous forty percent marks. The transition areas from the to stake have to be overlapped very well, otherwise the typical transition welts will accur.

Initially, immediately after the raisinig state, the raising welts should be removed in the forty percent planishing phase. This is best done across the welts. In a round domical form, the planishing may be radially or concentrically oriented. In a cylindrical form, triangular of the planishing marks is employed. Triangulation is effective on other forms also, for planishing as well as to check the forms themselves.

(Heikki Seppä, Form emphasis for metalsmiths, Second Edition, page 33)

Hoist

Load-suspensions parts of a manually operated hand chain hoist are the parts that are subject to direct load forces from the load attached to the load hook. Load- suspensions parts are the means of suspension, including the trolley,suspension hook, clevis or lug. The hoist frame which supports the load wheel, the load wheel, load chain, and the load block. Load suspension parts are normally designed so that the static stress calculated for the rated capacity load does not exceed 25% of the average ultimate strength of the material used for the parts. The resultant design factor is 4.

Standart models of manually operated hand-chain hoists are intended for general industrial use in ambient temperatures from O Fahrenait degree to 130 Fah. Enviramental conditions such as hazardous locations, excessively low or high ambient temperatures, corrosive fume atmospheres, dust-laden atmospheres, moisture-laden atmospheres, and exposure to outdoor-weather conditions that could be detrimental to a manually operated hand-chain hoist are considered abnormal operating conditions.

(Raymond A. Kulwiec, Material handling Handbook, Second edition, page 480-481)

DC Interfacing Motors

Controlling DC motors, the emphasis has been simple on-off type switching. It is possible with a digital system to actually provide speed control using a tecnique called pulse widht modulation.

With a DC motor, there are two technique for controlling the motor speed: The first is to reduce the DC voltage to the motor. The higher the voltage, the faster it will turn. At low voltages, the control can be a bit hit and miss and the power control is innefficient. The alternative technique called pulse widht modulation. (PWM) will control a motor speed not by reducing the voltage to the motor but the reducing the time that the motor is swithed on.

This is done by generating a square wave at afrequency of several hundreds hertz and changing the mark/space ratio of the wave form. With a large mark and the low space, the voltage is applied to the motor for almost all of the circle time, and thus the motor will rotate very quickly. With a small mark and a large space, the opposite is true. The diagram shows the waveforms for medium, slow and fast motor control.

(Steve Heath,Embedded system desing,Second Edition,page 185-186)

TRIP Steels

TRIP Steels (the acronym "TRIP" stands for TRansformation-Induced Plasticity) consist of ferrite, bainite and retained austenite. As for dual phase steels, the heat treatment starts by soaking in the intercritical (alfa and beta) region. In a second soaking step (usually around 350-400 Celcius), the reaming austenite is transformed into bainite, but the last friction austenite (5-10%)is maintained. the carbon content in this residual austenite is so high that is remains (meta)stable during cooling the room temperature. During subsequent cold forming, this metastable austenite will transform into martensite and this transformation assists the deformation.

TRIP Steels combine a high strength (600-1000MPa) with good ductility (total elongations around 30%) but with a low R-value (1-1.2).

(Bert Verlinden,Thermo-mechanical processing of metallic materials, 2007, page 416-417)