WWW.07MET.TK Casting & Working of Metals Lab Manuals
PRACTICAL # 7 PRACTICE OF MAKING SAND SAMPLES USING SAND RAMMER
Overview: The sand rammer is a machine for preparing specimens for testing of the permeability and strength of moulding sand and is comprised mainly of a base, ram, tamping bar and lever. The machine is so constructed that the ram is brought up by the crank and is then caused to drop to strike and drive down the tamping bar at the lower end of which is fixed a tamping plate which slides into a sand tube to press the sand tube into a certain size with certain energy.
Equipment: A. Sand Rammer B. Sand tube C. Sand stripping bar
Chemicals / Materials: Testing sand
Figure: Sand Rammer
WWW.07MET.TK Casting & Working of Metals Lab Manuals
Operating Procedure: Preparation of Strength Test Specimen: 1. Set the sand tube in the tube rest for about 15 mm, and holding it by hand, introduce about 140 g to 175 g of the test sand gently so that the sand surface is level. 2. Next, pull the handle toward you to force the tamping bar up, then load the sand tube having the sand charged together with the rest on the base, and introduce the ramming head quietly into the sand tube until it is held by the sand surface. 3. Then, turning the lever forward, perform ramming three times. 4. With the sand thus rammed, if the pointer provided on the tamping bar stops within the tolerable range on the scale, the compacted sand is usable as a test specimen of a standard size (height 50 mm). 5. The tolerances ±1 mm graduated above and below the base line, and if the pointer does not remain within the tolerable range, such specimen is not usable as a test specimen, so that it should be discarded. 6. Then, adjusting the quantity of sand to be introduced in the sand tube properly, repeat the foregoing procedure. 7. When a specimen of standard size is obtained, raise the ramming plate, remove the sand tube and set it over the sand stripping bar to withdraw the standard sand specimen from the sand tube.
Preparation of Permeability Test Specimen: 1. Set the sand tube on the rest, and prepare the test specimen, as in the case of the strength test specimen, with about 140 g to 175 g of the test sand fed. 2. The specimen height shall comply with the standard 50 mm (tolerance ±1 mm). 3. In the case of testing the permeability of green sand, the test specimen should not be withdrawn from the sand tube but be applied to the permeability tester immediately together with the sand tube.
Caution: The machine is subjected to considerable impact in use so that it should be installed in the rigid concrete base preferably in a height of 500600 mm.