11.4 Application
Tim A. Bacon
Now let’s go grind a bench block! The following is a step-by-step sequence of operations that can be directly applied to most projects.
- Safety first – Wear safety glasses, remove jewelry, and tie back loose clothing, and long hair.
- Gather equipment – Have some towels nearby to aid in coolant clean up. Create a clean location to place the tools.
- Choose a grinder – The workpiece is square, so use a horizontal surface grinder.
- Choose the wheel – The material for the Bench Block is mild steel. A straight grinding wheel will be used, with the cutting surface on the circumference of the wheel. The wheel is an Aluminum Oxide abrasive for the steel workpiece. A grit of 60 is for general purpose grinding applications.
- Perform a ring test – Ring test the grinding wheel before the wheel is placed on the spindle. If a high ring note is heard, proceed with installation. If the sound is dull, get a new wheel.
- Mount the wheel – The grinding wheel will be mounted on the grinding spindle. To tighten the nut that holds the wheel in place, turn it the opposite of the direction the grinding wheel turns when grinding. This nut usually has left-handed threads.
- Dress the wheel – Set the dressing diamond just past the center of the wheel, on the exit nip side (typically the left). Ensure that the magnet is on, and the diamond is secure. Start the wheel rotating by hand. With your hand clear of the wheel, turn on the power to bring the wheel up to speed. Bring the wheel down to just touch the diamond dresser. Move the crossfeed out towards the operator, and then in away from the operator to evenly dress the wheel. Bring the head down .0002 to .001 and move the crossfeed again. Repeat until the wheel is evenly cleaned up, then stop the wheel before continuing.
- Workholding – Ensure that the grinding wheel is not spinning; clean the table thoroughly. Place the part on the magnetic table with concave side down. Turn the magnet on, and check that the workpiece is secure.
- Touch off – While the wheel is stationary, bring the wheel head down slightly past the top of the part, and on the outgoing nip side of the wheel. “Gently”‘ move the table workspeed direction, X-axis, so that the part touches the wheel. Raise the head until the workpiece passes below the grinding wheel. This process stages the wheel within a few thousandths of the part to expedite grinding, and to avoid excessive plunging into the part on first contact.
- Instructor Note – Once a complete understanding of manually controlling the surface grinder is demonstrated, the automated functions can be introduced if the machine has the capability. Caution is strongly advised. If the grinder is not set correctly, the part may be destroyed, the machine may be damaged, and/or bodily harm may be caused to anyone nearby, including yourself.
- Turn on coolant – Position the coolant nozzle to spray at the ingoing nip side of the wheel on top of the workpiece.
- Turn the grinding