Injection Moulding Technology - Part 3 Welcomes you to Injection Moulding Technology - Part 3

Introduction Safety Telephones Registration Practical sessions Smoking Workshop access Refreshments Personal issues Messages Your contribution

Aim of course 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.

In your manual section 1, PAGE 8 Testing Through out the course there will be; Lesson Assessments Class Exercises Evening Assessments In your manual section 1, PAGE 8

Knowledge Assessment Conducted at the end of the course, successful completion of which: Awards a P.T.I.C Level 3 Polymer Processing Certificate. Will assist personnel working towards the achievement of an Injection Moulding Diploma 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.

Timetable 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 DAY 2 09:00 QUALITY(review evening assessments) 10:30 BREAK 10:45 MACHINE PRACTICAL No 1 12:30 LUNCH 13:00 SELF DEVELOPMENT (review morning session) 13:30 MACHINE PRACTICAL No 1 15:15 BREAK 15:30 MACHINE PRACTICAL No 1 16:45 FINISH

Timetable DAY 3 09:00 REVIEW HOME WORK 09:15 MOULD TOOLS 10:30 BREAK 10:45 POLYMER MATERIALS 12:30 LUNCH 13:00 SELF DEVELOPMENT (review morning session) 13:30 PROCESS & TROUBLESHOOTING 15:15 BREAK 15:30 PROCESS & TROUBLESHOOTING 16:45 FINISH

Timetable DAY 4 09:00 HOME WORK REVIEW 09:30 MACHINE PRACTICAL No 2 10:30 BREAK 10:45 MACHINE PRACTICAL No 2 12:30 LUNCH 13:00 SELF DEVELOPMENT (revision of course) 13:30 MACHINE PRACTICAL No 2 14:30 BREAK 14:45 DELEGATE FEEDBACK 15:00 END OF COURSE ASSESSMENT 17:00 FINISH

Injection Moulding Technology Part 3 Machine Construction Clamping End

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

Session objectives By the end of the session you will be able to: State the functions of the clamping unit. Name design alternatives for the clamp unit. Explain how to set and adjust the locking tonnage.

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

Terminology Mould Height Moving Half Fixed Half

Clamping end – Component Parts Moving Platen Mould Clamping Cylinder Ejection Fixed Platen Tie Bar

Direct hydraulic lock Single Hydraulic Cylinder

Direct hydraulic lock Advantages Disadvantages 1. Self lubricating 2. Low maintenance 3. Larger tonnages 4. Tonnage set more accurately and easier to adjust Disadvantages 1. Slower movements 2. Larger pumps 3. Seals expensive to replace 4. Increased power requirements

Setting the mould height

Tailplate position adjusted 1.0mm

High pressure applied 1.0mm

Toggle locking mechanism Spacer What if it doesn't reach ?

Hydraulic Driven Gear for Mould Height Adjustment Toggle Lock Machine

Double Toggle: Five point system

Toggle mechanism Advantages Disadvantages 1. Fast movements 2. Natural acceleration and deceleration 3. No forces on the clamping cylinder when locked. Disadvantages 1. High stress/strain 2. High maintenance 3. Links need lubrication 4. Usually smaller than 2200 Tonnes

Ejection methods

Clamp tonnage estimation Calculate projected area: x = 12in2 3 4 Rule of thumb = 2 - 4 tonnes/in2 x 4 = 48T Polycarbonate 12in2 3” 4” 480 KN

Clamp tonnage estimation Calculate projected area: x = 56cm2 7cm 8cm Rule of thumb = 0.3 - 0.6 tonnes/cm2 8cm 7cm x 0.3 = 16.8T POLYPROPYLENE 56cm2 168 KN

Clamp tonnage estimation To be used as a guide line only! CM = 0.3 0.4/0.5 0.6 Tonnes per Sq CM INCHES = 2 3 4 Tons per Sq Inch PP PE PA ABS PS POM PVC PC PMMA

Clamp end - 7 point plan Zero parameters Obtain movement Set positions Set speeds Set ejectors Set tonnage Check mould safety

Injection Moulding Technology Part 3 Machine Construction Injection End

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

Session objectives 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.

Reciprocating screw injection unit Feed Hopper Fixed Platen Reciprocating Screw Injection Cylinder Feed Throat Nozzle Drive Unit Barrel Heaters Barrel Check Valve Carriage Cylinder Carriage Complete the exercise in your course manual, Injection Unit Components.

Screw rotation What is back pressure? What is decompression?

General purpose screw Metering Compression Feed

Length to diameter ratio (LD ratio) Hopper Barrel Diameter 60mm Length 1200mm Length = 1200mm Diameter = 60mm L/D ratio = 1200/60 = 20:1

Compression ratio Compression ratio = 3:1 Volume in this flight = 1

The check ring

Nozzle & screw removal Heater Band End Cap Nozzle

Nozzle types Open Shut-off

Spring loaded shut-off nozzles

Hydraulic shut-off nozzles

Nozzle with too shallow a radius Nozzle seating Nozzle with too large a hole Correctly sized nozzle Nozzle with too shallow a radius Nozzle with too sharp a radius

What is specific pressure? Hydraulic pressures Maximum Pressure Switchover Point Set Injection Pressure 180 bar What is specific pressure? 90 bar Peak Pressure Holding Pressure Actual Pressure 50% Speed Injection Phase Holding Phase

Specific Injection Pressure Negri Bossi 100T Screw Diameter Hydraulic Pressure Intensification Factor Specific Inj.Pressure Shot Capacity 45 140 X 9.7 = 1358 72 35 140 2240 16 58 Screw Diameter = 45 mm (4.5 cm) Piston Diameter = 140 mm (14 cm) 1358 Bar Specific Pressure Hydraulic Pressure 140 Bar Screw area = 15.9 sq. cm Piston area = 153.9 sq. cm = 9.7 Intensification factor = Piston area = 153.9 sq. cm Screw area = 15.9 sq. cm

Hydraulic pressure - Specific injection pressure Specific pressure (in front off the screw) Typical 360 ton moulding machine psi bar 2100 2055 25000 1800 1500 1510 20000 70 dia (2.76 in.screw) 1200 1155 15000 60 dia (2.36in.screw) 80 dia (3.15 in.screw) 10000 600 5000 300 30 60 90 120 150 bar Reading at pressure gauge

Mould cavity specific pressure Flow path length = 200 mm Wall thickness = 1.5 mm 500 bar Specific pressure Material to be used is PVC

Projected area VS. clamp force Mould projected area = 600 Sq.cm Specific pressure was = 500 bar 300 tonne 3000 KN Use the charts provided in your course manual to complete the clamping force requirements.

Projected area 750 bar Specific pressure

Mould area VS. clamp force 90 tonne 900KN

Injection Moulding Technology Part 3 Machine Construction Injection End

Injection Moulding Technology Part 3 Machine Control & Instrumentation

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

Session objectives By the end of the session delegates will be able to: 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.

Machine control parameters Temperatures Times Positions Pressures Speeds

Machine control & instrumentation Question 1 A temperature closed loop control system can be divided into three areas. What are they?

Barrel temperature control Heater Closed Loop Controller Thermocouple

Factors affecting melt temperature Shear Back pressure Screw rotation speed Screw design Residence time Injection speed Ambient temperature Feed throat temperature

Question 2 Name three types of heater bands? Machine control & instrumentation Question 2 Name three types of heater bands?

Heater band types Mica Ceramic Ceramic (Knuckle) Aluminium

Question 3 How can shear heat be generated within the barrel? Machine control & instrumentation Question 3 How can shear heat be generated within the barrel?

Shear heat Frictional heat created by screw rotation Excess back pressure

Question 4 Name three designs of thermocouples? Machine control & instrumentation Question 4 Name three designs of thermocouples?

Thermocouples 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. Bayonet Fitting Armoured compensated leads Compression Type Ring Type

Question 5 What is the function of a thermocouple? Machine control & instrumentation Question 5 What is the function of a thermocouple?

Thermocouples are used to measure or sense temperature. Heater Controller T/C

Question 6 How does a thermocouple work? Machine control & instrumentation Question 6 How does a thermocouple work?

Thermocouples principle Metal 1 Cold junction Kon wire Fe wire Hot Millivoltmeter Calibrated in oc Cold Junction Hot Junction Metal 2 The potential difference (volts) can be related to the temperature difference.

Thermocouple output TYPE J - IRON/CONSTANTEN TYPE K - NICR /NIAL TEMP DEG C 200 220 240 260 MILLIVOLTAGE 10.777 11.877 12.998 14.108 TEMP Deg C 200 220 240 260 MILLIVOLTAGE 8.137 8.938 9.754 10.560

Thermocouples International colour codes for thermocouple identification T Y P E K NICKEL CHROME/NICKEL ALUMINIUM NiR/NiAL T Y P E J IRON CONSTANTEN I/C Fe/con Fe/CuNi

Machine control & instrumentation Question 7 Compare and contrast an ON/OFF temperature controller to a PID controller. Which one offers optimum control?

ON/OFF controller Potentiometric 200oC

Temperature controllers “PID control is very accurate at recording temperature” P.I.D (Proportional Integral Derivative) Hyperlinks on all of these !!!!

Proportional Droop error 200oC 100 10 30 50 70 90 % power

Proportional derivative Droop error 200oC 10 40 70 90 % power 100 Slow approach More power for longer

Proportional integral derivative 200oC 10 40 70 90 % power 100 Slow approach

Machine control & instrumentation Question 8 Name three types of position controllers? In addition, state which one of them is the most accurate way at providing actual feedback.

Positional control devices Roller Plunger Limit switches 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. Roller lever On/Off control

Proximity switch On/Off control

Linear Variable Differential Transducer LVDT Variable control

Rotary encoder LVDT Variable control

Question 9 List three functions of a timer and give examples. Machine control & instrumentation Question 9 List three functions of a timer and give examples.

Categories of time Categories Examples Normal times Supervisory times Delay times Holding time, cooling time, open cycle time Mould safety time, injection time, cycle time Delay screw back, Delay injection

Fundamental principles of speed & pressure Pressure is created by resistance to a flow of oil. Pressure is controlled within the hydraulics of an injection moulding machine by the use of pressure relief valves. The flow of oil is varied in the hydraulic circuit by the use of speed or flow control valves.

Pressure relief valve

Flow / Speed control valve

Proportional Speed Control Valve

Proportional Pressure relief valve

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

Hydraulic injection pressure Specific injection pressure 180 Bar 1800 Bar Specific injection pressure 10 : 1 Ratio 80 Bar 40 Bar Peak injection pressure 50 Bar If injection pressure is reduced what will happen?

Pressure affects flow (speed) Essential principle Remember! Pressure affects flow (speed)

The accumulator Dampen pulsation's and shocks within the system. Nitrogen pressure Nitrogen Bag 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. Pressure build up Oil flow

Mould fill and hold (Example - 4 impression mould) 160 bar Set values: Injection pressure = 160 bar (max) Injection speed = 50 % Hold pressure = 40 bar 90 bar Injection Pressure Holding Pressure 40 bar Machine Control Quiz (Pg. 59) Cushion Fill Time = 1.55 secs. 100mm 10mm Injection stroke - mould 99% full Hold position (switchover).

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

Injection Moulding Technology Part 3 Machine Control & Instrumentation

Injection Moulding Technology Part 3 Health & Safety

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

Session objectives By the end of the session you will be able to: Identify hazards associated with the injection moulding process. Name the safety systems required on a high risk guard. 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.

Please Note! 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.

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.

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.

Factories Act 1961 - Section 14 Machines made before 1993 governed by Factories Act This Act was only applicable until 1997 After 1997 the Factories Act, Section 14 ceased to be relevant to machine guarding The Factories Act was superseded by EC regulation ‘Work Equipment Regulations’ in 1993

Health & Safety - UK Legislation H.A.S.A.W.A. 1974 B.P.F. Code of Practice

Machine guards Normal Fixed High Fixed Fixed Fixed Fixed

Other guards Siemens Automotive

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.

Powers of the Inspector They can enter at any time. They can ask for an individual’s assistance. They can issue an improvement notice. They can issue a prohibition notice. They can prosecute anyone who has contravened a relevant statutory provision.

Corporate Social Responsibility

Injection Moulding Technology Part 3 Health & Safety

THE FACTORIES ACT 1961 SECTION 14 “Every dangerous part of any machine shall be securely fenced or safe by virtue of its position ”. Return

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.

HEALTH & SAFETY AT WORK ACT - 1974 Duties of Employees - Section 7 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 Not to endanger him-/herself or others by his/hers acts or omissions. Return

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