Computer-Controlled Machining. Group 1.

Week 7 group assignment Computer-Controlled Machining

We started with lab's safety training by two of our instructors in the lab. We used Rensi e2-1325 milling machine with vacuum table with mdf board (which is a type of porous wood). This machine is the most dangerous machine in our lab because it uses huge force to do milling. No one ever should operate this machine alone.

First we revised the safety instructions. * Wear safety glasses and hearing protection when operating the machine. * Put the safety shield between you and the machine. * Always be well rested and able to focus during milling. * Use the machine with a person who knows safety instructions, too. * Make sure no one goes too near to the machine. * Do not stay away off the pause and emergency stop buttons.

Picture1:CNC milling machine

Our instructors presented us the machine and went through the following steps:

• First power on the machine and the computer, and then open the software which is called NC Studio.
• Put the piece of wood that you want to mill. Wear gloves during this step so as not to get small pieces into your hand.
• Reset the axes by moving the milling head with either pressing the x and y axis buttons on the program, or with hand wheel device.
• If needed change the tool wearing gloves because the tool is sharp.
• Set up your piece on the table and attach it.
• Set the origin.
• Load the nc -file.
• Simulate.
• Run the work!

In the group work we used a 6mm, flat milling bit for wood. The milling bit had to be changed, and we watched our instructor to demonstrate the changing. You open up 2 switches that hold the casing to the milling bit. You drop it down, and then use two different kind of tools to let loose the milling bit and the socket it is in. Make sure that the removed part is clean because it affects the connectivity otherwise the machine will not stop when reaching the mdf layer and attach it tightly to the socket. Then just change the milling bit and click it back to the socket. It should be spinning around effortlessly. Then just reverse the process and put the tool back in.

replacing the milling bit

Our instructor had a piece of OSB that he wanted to cut a training equipment. The bed board is divided in to 4 different sections which use vacuum to suck the material down so that it doesn't move during the milling. The switches are found on the edge of the table, and the vacuum pumps are pressed on from the controlling unit. The wanted model to cut was not so big so we only used the first two vacuum valves.

Picture6:Vacuum bed valves

Picture7:Control unit

In the control unit there were for example the power switches, emergency stop, switch for vacuum pump and dust collector, and the computer.

Picture8:Switches for vacuum pumps and dust collector

In NC Studio we learned how to set the axes by moving the milling head buttons on the program and with hand wheel device. We set the origin with x and y axis, and used the mobile calibrating option in the program with a 40 mm tool to set the z also.

The file was loaded, vacuum and dust collector were on, so there was nothing else to do but to simulate the process in the program. Everything looked good in the simulation, so the milling could be started.

First the machine milled the pockets. After those it turned on to milling the outlines. Everything went just fine and the pieces were milled well. We were also shown how to clean after the job is done, and for example how to use the sander machine. Then we were off to take the measurements of the cut pieces.

Test piece measurements

Picture10:Test piece measurements

Table 1 Test piece measurements.

Test piece	outside width x height	inner cut	Cut width
Design (mm)	460 x 400	13	6
Milled piece (mm)	460 x 400	12.6	5.80