Injection Moulding Technology - Part 3

Injection Moulding Technology – IMT3

CoWC 0410

Injection Moulding Technology - Part 3Welcomes you to


CoWC 0410

Introduction

Messages

Smoking

Refreshments

Safety Telephones

Practical sessions

Workshop access

Personal issues

Your contribution

Registration


CoWC 0410

To provide delegates with an in-depth knowledge of the injection moulding process, in order to competently and safely set up a range of moulding machines, to achieve product quality and output.

Aim of course


CoWC 0410

Through out the course there will be;

Lesson AssessmentsClass Exercises

Evening Assessments

In your manual section 1, PAGE 8

Testing


CoWC 0410

Conducted at the end of the course, successfulcompletion of which:

Will assist personnel working towards the achievement of an Injection Moulding Diploma certificate.

Awards a P.T.I.C Level 3 Polymer Processing Certificate.

Allows progression onto practical element within Injection Moulding Technology - Part 3, resulting in the full award of a P.T.I.C Approved Technician.

Knowledge Assessment


CoWC 0410

DAY 1

09:00 ADMINISTRATION & INTRODUCTIONS

09:15 MACHINE CONSTRUCTION – CLAMP END

10:30 BREAK

10:45 MACHINE CONSTRUCTION - INJECTION END

12:30 LUNCH

13:00 SELF DEVELOPMENT (review morning session)

13:30 MACHINE CONTROL & INSTRUMENTATION

15:00 BREAK

15:15 MACHINE CONTROL & INSTRUMENTATION

16:00 HEALTH & SAFETY

16:45 FINISH (evening assessments and Quality)

Timetable


CoWC 0410

DAY 2

09:00 QUALITY(review evening assessments)

10:30 BREAK

10:45 MACHINE PRACTICAL No 1

12:30 LUNCH



15:15 BREAK


16:45 FINISH

Timetable


CoWC 0410

DAY 3

09:00 REVIEW HOME WORK

09:15 MOULD TOOLS

10:30 BREAK

10:45 POLYMER MATERIALS

12:30 LUNCH


13:30 PROCESS & TROUBLESHOOTING

15:15 BREAK

15:30 PROCESS & TROUBLESHOOTING

16:45 FINISH

Timetable


CoWC 0410

DAY 4

09:00 HOME WORK REVIEW


10:30 BREAK


12:30 LUNCH

13:00 SELF DEVELOPMENT (revision of course)


14:30 BREAK

14:45 DELEGATE FEEDBACK

15:00 END OF COURSE ASSESSMENT

17:00 FINISH

Timetable


CoWC 0410

Injection Moulding Technology

Part 3

Machine Construction

Clamping End


CoWC 0410

To provide an in-depth understanding of the clamp unit construction, operation and setting, including variations in terminology.

Session aim


CoWC 0410

Name design alternatives for the clamp unit.

Explain how to set and adjust the locking tonnage.

State the functions of the clamping unit.

By the end of the session you will be able to:

Session objectives


CoWC 0410

Terminology

Whenever possible: Daylight = 2-3 x depth of moulding


CoWC 0410

Terminology

Mould Height

Fixed HalfMoving Half


CoWC 0410

Clamping end – Component Parts

Moving Platen

Fixed Platen

Tie Bar

Mould Clamping Cylinder

Ejection


CoWC 0410

Single HydraulicCylinder

Direct hydraulic lock


CoWC 0410

1. Self lubricating2. Low maintenance3. Larger tonnages4. Tonnage set more accurately and easier to adjust

1. Slower movements 2. Larger pumps 3. Seals expensive to replace 4. Increased power requirements

Advantages

Disadvantages

Direct hydraulic lock


CoWC 0410

Setting the mould height


CoWC 0410

1.0mm

Tailplate position adjusted


CoWC 0410

1.0mm

High pressure applied


CoWC 0410

SpacerWhat if it doesn't reach ?

Toggle locking mechanism


CoWC 0410

Hydraulic Driven Gear for Mould Height Adjustment Toggle Lock Machine


CoWC 0410

Double Toggle: Five point system


CoWC 0410

1. Fast movements2. Natural acceleration and deceleration3. No forces on the clamping cylinder when locked.

Advantages

Disadvantages1. High stress/strain2. High maintenance3. Links need lubrication4. Usually smaller than 2200 Tonnes

Toggle mechanism


CoWC 0410

Ejection methods


CoWC 0410

Rule of thumb = Rule of thumb = 2 - 4 tonnes/in2

480 KN480 KN

3”4”

Calculate projected area: x =12in234

x4 = 48T

Polycarbonate

12in2

Clamp tonnage estimation


CoWC 0410

Rule of thumb = Rule of thumb = 0.3 - 0.6 tonnes/cm2

168 KN168 KN8cm

7cm

Calculate projected area: x = 56cm27cm8cm

x 0.3 = 16.8T

POLYPROPYLENE

56cm2



CoWC 0410


To be used as a guide line only!

CM =

INCHES =

0.4/0.5

3

0.6 Tonnes per Sq CM

4 Tons per Sq Inch

PPPEPA

ABSPSPOM

PVCPCPMMA

0.3

2


CoWC 0410

Clamp end - 7 point plan

• Zero parameters• Obtain movement• Set positions• Set speeds• Set ejectors• Set tonnage• Check mould safety


CoWC 0410

Injection Moulding TechnologyPart 3

Machine ConstructionInjection End


CoWC 0410

To provide an understanding of the construction, operation, setting up and terminology, relevant to the injection unit of the moulding machine.

Session aim


CoWC 0410

At the end of this session you will be able to:

Describe the basic construction of the injection unit.

Name three zones of a general purpose screw.

Describe the design of PVC and Nylon screws.

Identify the function of injection unit process parameters.

List commonly used nozzle designs and describe their application.

Explain the term “specific injection” pressure.

Session objectives


CoWC 0410

Reciprocating screw injection unit

Fixed Platen

Nozzle

Reciprocating Screw

Feed Hopper

Feed Throat

Drive Unit

Injection Cylinder

CarriageCarriage Cylinder

Barrel Heaters

Check Valve

Barrel

Complete the exercise in your course manual, Injection Unit Components.


CoWC 0410

What is back pressure?

Screw rotation

What is decompression?


CoWC 0410

FeedCompressionMetering

General purpose screw


CoWC 0410

HopperBarrel

Diameter

Length 1200mm

60mm

Length = 1200mmDiameter = 60mmL/D ratio = 1200/60 = 20:1

Length to diameter ratio (LD ratio)


CoWC 0410

Compression ratio

Volume in this flight = 1 Volume in this flight = 3

Compression ratio = 3:1


CoWC 0410

The check ring


CoWC 0410

Nozzle & screw removal

Heater BandEnd Cap

Nozzle


CoWC 0410

Open

Shut-off

Nozzle types


CoWC 0410

Spring loaded shut-off nozzles

Shut-off


CoWC 0410

Hydraulic shut-off nozzles


CoWC 0410

Nozzle seating

Correctly sizednozzle

Nozzle with toolarge a hole

Nozzle withtoo sharp a radius

Nozzle with too shallow a radius


CoWC 0410

180 bar

50%Speed

Injection Phase Holding Phase

Set Injection Pressure

Holding Pressure

MaximumPressure Switchover Point

ActualPressure

What is specific pressure?

Hydraulic pressures

90 barPeak Pressure


CoWC 0410

Negri Bossi 100TSpecific Injection Pressure

Screw area = 15.9 sq. cm Piston area = 153.9 sq. cm

Screw Diameter= 45 mm (4.5 cm)

Piston Diameter= 140 mm (14 cm)

ShotCapacity

72

35 140 224016 58

SpecificInj.Pressure

1358

ScrewDiameter

45

HydraulicPressure

140

Intensification Factor9.7

1358 Bar

Specific Pressure

Hydraulic Pressure140 Bar

X =

= 9.7Intensification factor = Piston area = 153.9 sq. cm Screw area = 15.9 sq. cm


CoWC 0410

Specific pressure(in front off the screw)

Typical 360 tonmoulding machine

2055

1510

1155

barpsi2100

1800

1500

1200

600

300

25000

20000

15000

10000

5000

0 30 60 90 120 150 bar

60 d

ia (2

.36i

n.sc

rew

)70

dia

(2.7

6 in

.scr

ew)

80 dia (3.15 in

.screw)

Reading at pressure gauge

Hydraulic pressure - Specific injection pressure


CoWC 0410

500 barSpecificpressure

Mould cavity specific pressure

Flow path length = 200 mm

Wall thickness = 1.5 mm

Material to be used is PVC


CoWC 0410

300 tonne3000 KN

Projected area VS. clamp force

Mould projected area = 600 Sq.cm

Specific pressure was = 500 bar

Use the charts provided in your course manual to complete the clamping force requirements.


CoWC 0410

750 barSpecificpressure

Projected area


CoWC 0410

90 tonne900KN

Mould area VS. clamp force


CoWC 0410


Machine ConstructionInjection End


CoWC 0410


Machine Control &

Instrumentation


CoWC 0410

To provide an understanding of process parameters and machine control devices to enable effective setting of the injection moulding machine.

Session aim


CoWC 0410

State the 5 control parameters for injection moulding

Describe how basic flow and pressure valves operate

Identify 4 types of positional control devices

State 3 types of injection moulding machine timer control devices.

Describe the relationship between pressure & speed within a hydraulic system of an injection moulding machine.

Session objectives

By the end of the session delegates will be able to:


CoWC 0410

Temperatures

Times

Positions

Pressures

Speeds

Machine control parameters


CoWC 0410

Machine control & instrumentation

Question 1

A temperature closed loop control system can be divided into three areas. What are they?


CoWC 0410

ClosedLoop

Heater

ThermocoupleController

Barrel temperature control


CoWC 0410

Shear Back pressure Screw rotation speed Screw design

Residence time

Injection speed

Ambient temperature

Feed throat temperature

Factors affecting melt temperature


CoWC 0410


Question 2

Name three types of heater bands?


CoWC 0410

Mica

Ceramic

Ceramic (Knuckle)

Aluminium

Heater band types


CoWC 0410


Question 3

How can shear heat be generated within the barrel?


CoWC 0410

Shear heat

Frictional heat created by screw rotation

Excess back pressure


CoWC 0410


Question 4

Name three designs of thermocouples?


CoWC 0410

Where a pocket cannot be created, a band type thermocouple might be used, and where the temperature of a fluid is to be measured, one might resort to a leak proof compression fitting thermocouple.

Thermocouples

Ring Type

Compression Type

BayonetFitting

Armoured compensated leads


CoWC 0410


Question 5

What is the function of a thermocouple?


CoWC 0410

Thermocouples are used toThermocouples are used to measuremeasure oror sensesense temperature.temperature.

Heater

T/CController

Thermocouples


CoWC 0410


Question 6

How does a thermocouple work?


CoWC 0410

The potential difference(volts) can be related to the temperature difference.

Thermocouples principle

Metal 1

HotJunction

Metal 2

ColdJunction

Cold junction

Kon wire

Fe wire

Hot junction

MillivoltmeterCalibrated in oc


CoWC 0410

TYPE J - IRON/CONSTANTEN

TEMP DEG C

200220240260

MILLIVOLTAGE

10.77711.87712.99814.108

TYPE K - NICR /NIAL

TEMP Deg C

200220240260

MILLIVOLTAGE

8.1378.9389.754

10.560

Thermocouple output


CoWC 0410

International colour codes for thermocouple identification

TYPE

J

TYPE

K

NICKEL CHROME/NICKEL ALUMINIUM NiR/NiAL

IRON CONSTANTEN I/C Fe/con Fe/CuNi

Thermocouples


CoWC 0410


Question 7

Compare and contrast an ON/OFF temperature controller to a PID controller. Which one offers optimum control?


CoWC 0410

Potentiometric

200oC

ON/OFF controller


CoWC 0410

Temperature controllers

P.I.D (Proportional Integral Derivative)

“PID control is very accurate at recording temperature”


CoWC 0410

200oC

100

1030507090

Droop error

% power

Proportional


CoWC 0410

200oC10407090

Droop error

100Slow approach

More power for longer

% power

Proportional derivative


CoWC 0410

200oC10407090

100

Slow approach

% power

Proportional integral derivative


CoWC 0410


Question 8

Name three types of position controllers? In addition, state which one of them is the most accurate way at providing actual feedback.


CoWC 0410

Limit switches are micro switches, which automatically start and stop the movements of the machine.

They may be of the plunger, roller or roller lever type.

Limit switchesLimit switches

On/Off control

Positional control devices

Plunger

Roller lever

Roller


CoWC 0410

On/Off control

Proximity switch


CoWC 0410

LVDT

Variable control

Linear Variable Differential Transducer


CoWC 0410

LVDT

Variable control

Rotary encoder


CoWC 0410


Question 9

List three functions of a timer and give examples.


CoWC 0410

Categories

Mould safety time,injection time, cycle time

Normal times

Supervisory times

Delay times Delay screw back,Delay injection

Holding time, cooling time,open cycle time

Examples

Categories of time


CoWC 0410

Pressure is controlled within the hydraulics of an injection moulding machine by the use of

pressure relief valves.

Pressure is created by resistance to a flow of oil.

Fundamental principles of speed & pressure

The flow of oil is varied in the hydraulic circuit by the use of speed or flow control valves.


CoWC 0410

Pressure relief valve


CoWC 0410

Flow / Speed control valve


CoWC 0410

Proportional Speed Control Valve


CoWC 0410

Proportional Pressure relief valve


CoWC 0410

Moog valveMicroprocessor electronics which enables connection to a PC, for remote or on-site diagnostic correction!


CoWC 0410

Hydraulic injection pressure

180 Bar

Peak injection pressure

50 Bar

80 Bar

40 Bar

1800 Bar

Specific injection pressure

10 : 1 Ratio

If injection pressure is reduced what will happen?


CoWC 0410

Pressure affects flow (speed)

Remember!

Essential principle


CoWC 0410

Dampen pulsation's and shocks within the system.

Allow immediate operation of a service on demand.

Stores oil under pressure.Provides high rate, hence

high actuator speed.

Bag

Nitrogenpressure

Pressure build up

Nitrogen

Oil flow

The accumulator


CoWC 0410

(Example - 4 impression mould)

160 bar

90 bar

InjectionPressure

100mmInjection stroke - mould 99% full10mmHold position(switchover).

0

Cushion

HoldingPressure

40 bar

Set values:Injection pressure = 160 bar (max)Injection speed = 50 %Hold pressure = 40 bar

Fill Time = 1.55 secs.

Mould fill and hold


CoWC 0410

Injection end - 7 point plan

Set shot weight & hold pressure position

Set screw speed

Set injection speed

Set injection pressure

Set injection & hold times

Set cooling time

Set injection initiation


CoWC 0410

Machine Control &

Instrumentation


Part 3


CoWC 0410


Part 3

Health & Safety


CoWC 0410

To provide an overview of the safety requirements, relevant to the injection moulding industry.

Session aim


CoWC 0410

By the end of the session you will be able to:

State a duty of the employee and employer under HASAWA 1974.

List the necessary guard check requirements, as stated within the BPF Code of Practice.

Name the safety systems required on a high risk guard.

Identify hazards associated with the injection moulding process.

Session objectives


CoWC 0410

The information presented during this training programme is provided in good faith and for the guidance of the delegates.

Polymer Training accept no responsibility for alterations to legislation, which may have occurred without prior knowledge of the Polymer Training representative.

Please Note!Please Note!


CoWC 0410

A Rochdale plastics manufacturer has been fined £140,000 after a Portuguese cleaner was crushed to death by a pallet of bags

weighing nearly one and a half tonnes.


CoWC 0410

• Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR) Change – 6 April 2012

• From 6 April 2012, subject to Parliamentary approval, RIDDOR’s over three day injury reporting requirement will change. From then the trigger point will increase from ‘over three days’ to over seven days’ incapacitation (not counting the day on which the accident happened).

• Incapacitation means that the worker is absent or is unable to do work that they would reasonably be expected to do as part of their normal work.

• Employers and others with responsibilities under RIDDOR must still keep a record of all over three day injuries – if the employer has to keep an accident book, then this record will be enough.

• The deadline by which the over seven day injury must be reported will increase to 15 days from the day of the accident.

• New guidance that explains the change will be available to download from the HSE website on 16 January 2012.


CoWC 0410

Factories Act 1961 - Section 14

After 1997 the Factories Act, Section 14 ceased to be relevant to machine guarding

This Act was only applicable until 1997

Machines made before 1993 governed by Factories Act

The Factories Act was superseded by EC regulation ‘Work Equipment Regulations’ in 1993


CoWC 0410

Health & Safety - UK Legislation

B.P.F. Code of Practice

H.A.S.A.W.A. 1974


CoWC 0410

Machine guards

Fixed

Fixed

HighFixed

Fixed Fixed

Normal


CoWC 0410

Siemens Automotive

Other guards


CoWC 0410

Policing the law

The HSE have compiled their own guidance sheets, that relate to various processes. These can be obtained directly from the HSE and are deemed to be the minimum requirements.


CoWC 0410

Powers of the Inspector

They can enter at any time.

They can ask for an individual’s assistance.

They can issue a prohibition notice.

They can issue an improvement notice.

They can prosecute anyone who has contravened a relevant statutory provision.


CoWC 0410

Corporate Social Responsibility


CoWC 0410


CoWC 0410


Part 3

Health & Safety


CoWC 0410

THE FACTORIES ACT 1961

SECTION 14

“Every dangerous part of any machine shall be securely fenced or safe by virtue of its position ”.

Return


CoWC 0410

HEALTH AND SAFETY AT WORK ACT - 1974

Duties of Employers - Section 2

To ensure the health and safety of all employees by providing:

Safe plant and systems of work.

Safe handling, storage and transport.

Information, instruction, training and supervision.

Safe access and egress.

A maintained and healthy working environment.


CoWC 0410

Duties of Employees - Section 7

Return

Not to misuse anything provided in the interest of health and safety.

To report any unsafe situation.

To co-operate with the employer in matters of health and safety.

Not to endanger him-/herself or others by his/hers acts or omissions.

HEALTH & SAFETY AT WORK ACT - 1974


CoWC 0410

B.P.F CODE OF PRACTICE

The B.P.F. Code of Practice is NOT a statutory requirement, but it may be used in criminal proceedings as evidence, together with other regulations, stating that statutory guarding requirements have been contravened.

This code may be used by H.M. Safety Inspectorate as a basis for it’s enforcement procedures.

Return

Injection Moulding Technology - Part 3

Documents