P & P Precision Designs Ltd.
Buttwelder Mk 2 1500 Wide
Mechanical
Operating Instructions
Issue 1 - March 2001

CONTENTS

Part 1     INTRODUCTION

Part 2     CAPABILITIES OF THE P & P MK 2 BUTTWELDER

Part 3     MACHINE OPERATION

Part 4     HEALTH AND SAFETY

Appendices: BUTTWELDING CONDITIONS

Appendix 1     LD based products
Appendix 2     EV and VA based products
Appendix 3     HD and HL based products

PART 1 INTRODUCTION

Butt-Welding is the process of joining butt surfaces (edges) together by heat to form rolls of material with a weld equivalent in strength to that of the individual sheets. The machine clamps the two blocks of foam, then compresses the edges together, then uses an electrically heated blade that passes along the joint to weld the butt surfaces:-

i) Density: High density grades require more heat to melt an equivalent surface area.

ii) Grade: Amount of heat required to melt a sheet surface depends upon the melt properties of the base polymer e.g. HDPE has a higher melting temperature range than LDPE.

iii) Butt Contact Pressure: Amount of pressure applied to the joint, this is determined by how the machine is calibated.

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PART 2 CAPABILITIES OF THE P&P MK 2

BUTTWELDER

2.1 Use of Buttwelder

The machine is designed to weld Plastazote, Evazote and Supazote foam grades produced by Zotefoams.

2.2 Width

Maximum foam width of up to 1500mm can be welded.

However there are other factors which affect the laminated width achievable which are not related to the design of the Buttwelder. The maximum width achievable depends upon the squareness of the sheets at the edges and the alignment of the edges as they are being fed-in.

Misalignment becomes more important when building up long reels as the roll will not continue straight and true along the length.

2.3 ButtWelded reel length

The only limit to the length of the reel that can be produced the difficulty of handling long reels and ideally this requires specialised handling equipment.

2.5 Thin sheet foam

Altering the height of the top clamps to accommodate foam thinner than 30mm will render the machine potentially unsafe – The CE Mark and hence the minimum closure distance of the clamps (25mm) has been determined using EN 294, ‘Safety Distances to Prevent Danger Zones Being Reached By Upper Limbs’.

2.6 Rate of ButtWelding

This is controlled by the speed of the traversing blade, which is adjustable from the contol console.

2.7 ButtWelding Temperatures

Temperature can be set in 1°C increments up to a maximum of 550°C, which is adjusted from the temperature controller on the console. There are specific temperatures for particular materials, as shown in the appendices, however, these can altered to suit particular requirements.

2.8 Weld hold time

Because this is similar for most materials, ie. 5 seconds, the machine is set this way as standard. This can be adjusted to particular requirements using the E-200 user interface. Please refer to the ‘Electrical and Control Manual’

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PART 3 MACHINE OPERATION

3.1 Introduction to Operation

The ButtWelder operates by clamping two sheets of foam on either side of the electrically heated blade. The ‘Butt’ surfaces are compressed together and the heated blade then passes across the join, welding the sheets together .

3.1.1 General Operation

Before attempting to operate the ButtWelder the user must be fully conversant with the Health and Safety Section (Part 4) of these instructions as well as being fully familiar with the location of the Emergency Stop button and all the operational buttons and switches.

The Emergency Stop button isolates power to all of the active systems and the heater blade.

The Emergency Stop button is also used to put the machine into standby mode.

3.1.2 Sequence of Operation

a. Turn on machine and allow blade to reach set temperature.
b. Reset the machine using the Joy-Stick.
c. Push in foam to either side of machine, ensuring foam is spread evenly over clamp-feet-pairs and butted-up to the spacer.
d. Clamp down using Right Clamp Down Joy-Stick.
e. Carry out same procedure for Left Clamp Down.
f. Start weld sequence using Joy-Stick.
g. Allow weld sequence to complete.
h. Clamps will automatically release after a set delay.
i. Remove the two joined pieces from the machine.
j. Reset using the Joy-Stick.

3.1.3 Sheet Feeding

Foam guides are located at each side of the machine to ensure sheets of foam line
Up. At the start of production of a new batch, these guides should be adjusted
According to the width of foam being welded.

3.1.4 Foam Characteristics.

Successful ButtWelding relies upon the contact surface maintaining even heat transfer. The heat transfer from the blade depends upon :-

i) Density High density grades require more heat to melt the surface.

ii) Grade Heat required to melt sufficient of the material surface depends upon the melt characteristics of the grade.

iii) Contact Surface area in contact pressure with the blade depends upon the Gap Settings (Figure 1).

3.2 Blade temperature

3.2.1 Adjusting the Temperature Controller

The set temperature is controlled and adjusted by a Temperature control unit.

With power on, two temperatures are continuously displayed, the lower being the `Desired Temperature', the upper the actual blade temperature.

The `Desired Temperature' is adjusted by the operator touching the front of the panel below the displayed temperatures. The up and down buttons will illuminate and pressing either button will change the set point value. Short presses change the set point by single units. Long presses accelerate the set point for large adjustments.

3.2.2 Setting the Correct Buttwelding Temperature.

i) Temperatures must first be set up as specified in the Appendix for the specific grade and thickness.

ii) After start-up from cold allow heated blade to maintain set temperature before using.

3.2.3 Using Temperatures Higher than the Operating Temperatures

Setting the temperature slightly higher than indicated in the Appendices may improve the weld when sheets are uneven. However, in excess of 20°C - 68°F higher may result in unsatisfactory weld quality.

i) The blade temperature should be kept as low as possible. In the event of the blade becoming trapped while in contact with the blade, the higher the temperature the greater the risk of fire.

ii) Unnecessary over-heating of material may give a thicker, darker, more prominent weld line.

iii) Material will be more prone to sticking to the blade and uneven melt-back will be more likely to occur; i.e., gaps and solid lumps giving very poor quality weld.

iv) Over-heating and material sticking to the blade will result in the emission of excess smoke and fumes.

3.3 Blade Traverse speed

3.3.1 Adjusting the Blade Speed

The 0-99 touch-dial on the operators console controls the speed of the blade:-

The machine is normally used at full speed, although, the speed can be lowered to suit particular requirements.

3.4 Foam Dimensional Tolerances

3.5 Butt-Welding dissimilar materials together

Use the conditions for the foam with the highest set points, ie. The highest temperature and the slowest blade speed.

Figure 1 - Table Compression adjustments

3.6 Compression adjustment

Altering the location of the shock absorber (Fig 1) allows the contact pressure to be altered.

The greater the distance the greater the stroke of the cylinder.

When resetting this distance ensure all four are set to exactly the same distance.

3.6 Table position adjustment

This is adjusted at the connection to the pneumatic cylinder. This should never need to be altered. If adjustments are made for any reason, such as for maintenance, ensure they are repositioned exactly. Failure to do so could cause catastrophic damage to the machine.

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PART 4 HEALTH AND SAFETY

Any machine can be dangerous if improperly used.

Safe working practice is the responsibility of the user.

Note that this machine contains pneumatic clamps and a hot blade that must not be touched.

 

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APPENDIX 1

TABLE 1.1 : Traversing Blade Butt Welder Conditions for LD based products

Materials with ‘Stike-through’ (LD24LC) have not been tested for Buttwelding as they were deemed unsuitable for producing reels.

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APPENDIX 2

TABLE 2.1 : Traversing Blade Butt Welder Conditions for EV & VA based products

Materials with ‘Stike-through’ (LD24LC) have not been tested for Buttwelding as they were deemed unsuitable for producing reels.

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APPENDIX 3

TABLE 3.1 : Traversing Blade Butt Welder Conditions for HD and HL based products

Materials with ‘Stike-through’ (LD24LC) have not been tested for Buttwelding as they were deemed unsuitable for producing reels.

PLASTAZOTE, EVAZOTE and SUPAZOTE are registered trade marks of Zotefoams plc

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