NVQ witness testimony example

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

BENDING RIG PLATE Job description: To mill one plate of mild steel to size and drill holes and pocket as specified in the drawing. The finished part would make up the base of a bending rig that would be used to test tensile samples. The job would be made on a CNC machine; in this case the machine was a DMG 1035 V eco, which uses a Heidenhain-Siemens control panel. The job card I was given and the corresponding drawings are pictured below.

The job card is pictured above.

Page | 1

NVQ WRITE UP

CNC MILLING

The Assembly drawing is pictured above.

The DMG 1035 evo that I used is pictured above. Page | 2

STEFANOS KOUSOULAS

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

The 330X125X20(mm) Mild steel plate is pictured above.

Set up/preparation: The setup of my job was crucial. Not only for the quality of my job and my safety but also because of the machine I was using. Using a CNC machine requires patience, logic and trust. CNC machines generally tend to be very expensive and delicate/fragile; so maintenance, repair and replacement parts are just as expensive. The machine I worked on can work at very high speeds and RPM’s so I constantly needed to be watching and using the feed and rapids to ensure a problem free machining experience.

When setting up my job I used a vice that was clamped down with four clamps; the vice also had two ground tenons in purposely machined grooves under the clamp, meaning it was relatively square, however, I still used my dial test indicator to clock and square up the vice. I made sure to clean the table of the machine to endure no chips or rust had collected, before clamping down and setting up the vice. I also used some machine jacks to stop the part from vibrating when being machined because it was quite big. Page | 3

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

The vice, parallels and jacks setup pictured above. Once the vice was set up I used two 4” parallels to sit my job onto. I lightly clamped the vice. I then used a rubber dead blow hammer to gently tap the job; making sure that is was properly seated on the parallels. I knew the job was well seated when I could not move the parallels, at this point I set the vice to setting 2 (2 tonne), and tightened it until the handle became loose, showing the vice had reached 2 tonne of clamping force.

The job in the vice is pictured above.

Page | 4

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

I had to turn the onto its sides to machine the longest edges down to side, so it meant re setting the job up in the vice, this time I didn’t use parallels. I used a universal taster probe to set the reference (datum) points on the job. The universal taster is used to set reference points and can be seen in use by myself below; the hand wheel is used to manually move the taster probe.

Page | 5

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

The setup of the second face milling cycle is pictured below.

Process: First I had to start by writing the program cycles for machining. I had various cycles to write, they included face milling, end milling, chamfer, pocket and drilling programmes. All of the programmes worked from a datum that was set to the centre of the job. The first two face milling programmes involved milling a total of 5mm off the top and bottom faces of the plate so it would to size at 15mm thick. The heidenhain-seimens controller is a very powerful system, it uses both external programming and shopmill, which means simple programming i.e. face milling programmes can be written on the machine.

Page | 6

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

The control panel can be seen below.

To face mill the two faces I used a 60MM indexable face mill that uses 5 carbide tips as cutting edges. I ran the program at a speed of 1000RPM and feed of 200mm/min for roughing and 3000RPM and a feed of 200mm/min for the finishing cuts. I used these speeds and feeds for roughing and finishing for the rest of my cycles as they are standardised/recommended cutting speeds for the material criteria and are far below the actually cutting capabilities of the tooling.

Page | 7

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

The picture above shows the face milling programme in progress, it also shows the coolant that is used which is fuchs ecocool oil mixed with water at 4% dilution. Once the two faces were machined, making the block 15mm thick, I used a chamfer programme that I had pre-written, to put a 0.5mm chamfer around the block. The chamfer was not only to show professionalism but also for safety, as it removes burrs and sharp edges.

The chamfer tool can be seen above. Page | 8

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

Next was the face milling cycles for the longest top and bottom faces, Once set up I wrote yet another face milling program to machine the width of the block down to 120mm. I machine 1mm of the first face, then 4mm off the next face. The programme can be seen running below.

I then re-wrote the chamfer programme to ensure all edges of the block were chamfered. I then had to end mill the last two edges, clamping on the newly machine faced to ensure the block was square and accurate. The end mill programme was also wrote using shop-mill (below)

Page | 9

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

The surface finish can be seen below.

I used a 750mm vernier calliper, a depth micrometer for the pockets, and various size micrometers to measure the block as I progressed.

The 750mm vernier calliper can be seen above.

Page | 10

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

The last program was the pocket and holes. This was again written using shop mill, the pocket was 5mm deep and had to be 95X250mm. The programme can be seen below.

I can be seen setting the block up and changing the datum manually below.

Page | 11

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

I had to reset all datum’s to ensure the block would be machined precisely and accurately, the image below shows me using the manual hand wheel to re-set the datum’s using the universal taster probe.

The machine can be seen milling the pockets below.

Page | 12

NVQ WRITE UP

CNC MILLING

The finished product can be seen below.

The working bending rig and assembled work pieces can be seen below.

Page | 13

STEFANOS KOUSOULAS

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

PPE & Risk assessment: The PPE (personal protection equipment) is vital for the health and safety of the operator, health and safety laws and regulations state that PPE must be provided for operators of dangerous machinery to prevent injuries and ill health caused by the nature of work. The chips made by the machining are collected at the bottom of the machine, I used a dustpan and brush to collect the chips and emptied them into a swarf bin. The PPE I wore are as follows:  





Safety glasses – Safety glasses are used to protect the eyes from any projectiles that might possibly be launched towards you i.e. chips/swarf. Safety boots – Safety boots have steel toe caps that protect the feet/toes from any falling objects, broken feet and toes used to be a massive issue in warehouses and factories because of heavy objects falling on people’s feet, so steel toe cap boots have become PPE necessary for people who work with heavy objects and machinery. Safety gloves – Gloves are used to protect the hands from sharp edges and burrs, and depending on what the gloves are made of they can also offer protection to chemicals (Nitrile gloves.) Chainmail gloves can be used to protect against blades. Laboratory coat – A laboratory coat offers protection to clothing from anything that might usually have landed on clothing, as well as making the operator look more professional.

Safety Gloves and glasses can be seen below.

Page | 14

NVQ WRITE UP

CNC MILLING

My safety boots are pictured below.

My lab coat and safety glasses is pictured below.

Page | 15

STEFANOS KOUSOULAS

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

The E-stop key and safety features of the machine can be seen pictured below.

Page | 16

NVQ WRITE UP

CNC MILLING

STEFANOS KOUSOULAS

I had pre-existing risk assessments for using CNC machining centres, and the corresponding COSHH (control of substances hazardous to health) and SSOW (Safe systems of work.) The cutting fluid used is stored in barrels that are stored in chemical cupboards. Any dirty coolant is removed from the machine and put into and IBC.

The pre-existing risk assessment can be seen above.

Page | 17