Tài liệu Ktf_9_prozesstechnik_final

Adhesive Manufacturing Processes Chapter 9: Process Technology Univ.-Prof. Dr.-Ing. Prof. h.c. Stefan Böhm Department for Cutting and Joining Manufacturing Processes (tff) University of Kassel, Germany Quelle: Wikipedia Agenda  Introduction  Storing, Conveying  Mixing  Dosing, Application  Joining, Fixation  Curing, Handling 2 Introduction  Process technology for handling of adhesive primarily dependent on: ● Production technology, state on delivery (e.g. viscosity) ● Batch size (small-, medium- oder big batch production) ● Possibility of automation of adhesive process ● Circumstances in area of use (tools available, environmental conditions etc.) ● Ecological factors (containing solvent) 3 Einleitung Stress • • • mechanical • • • • • • • Adhesion tension Compression peeling crash On adherend On pre-treated surface • • • • • • chemical Climate thermal (changing) filling, coating Spray-coating, airless 1C-, 2C- batching devices Dip-Coating Mesh-printing Stamp-printing Solvent containing adhesives Degreaser (FKW, CKW) Pre-treatment dipping Curing Application • • • Environment Optics • • functional decorative Curing Time • • • Pot Life Gelation Time Complete Curing Time • • • • • • • • • • Ambient Temperature Oven IR-Emitter UV-Emitter Electron Beam Induction Microwaves Initiator 2. Component Anaerobic conditions 4 Introduction  Process Flow for adhesive bonding Stocking Up / Storing Conveying Mixing Conveying Application Joining Fixation Curing Handling 5 Agenda  Introduction  Storing, Conveying  Mixing  Dosing, Application  Joining, Fixation  Curing, Handling 6 Storing & Conveying  Storing & Converying of adhesives mostly dependend on components, curing conditions & production e.g. limited shelf life or special specifications for storing temperature  Differentiation between three states of adhesives: 1. liquid 2. Paste-like 3. solid 7 Storing & Conveying 1. Liquid ● Possibility of separation or thickening due to long or leaky storing conditions (phase transitions)  Homogenisation by mixing – Manual Agitator – Air Pressure powered agitator – Electrical powered agitator ● Some conditions may require constant agiation (e.g. when solid components like Siliciumcarbide-powder tend to sink) Quelle: Endlich 8 Storing & Conveying 1. Liquid ● Different storing possibilites: Open falling container Quelle: Endlich Pre-pressurised Container with riser Pre-pressurised Container with plunger Pre-pressurised Container with bottom pipe Mechanical plunger pump Conveying of Adhesive: Container equipped with valve  lower/excess pressure required. 9 Storing & Conveying 2. Paste-like ● Adhesives with high viscosity ● Hardly any separation of components ● Problem: Conveying  viscous input of heat necessary ● Most commom stored in heatable barrels (see figure) Heated hose and barrel Quelle: Endlich und http://www.elkume.at/new-page/fassheizungen.html 10 Storing & Conveying 3. Solid ● Available types of hot melt adhesives: – Granulate – Filament – Zylindric cartridge (see figure) – Cartridge filling  Usage depends on the form of supplay and user tool Hotmelt application device, adhesive is inserted as a ‚stick‘ Quelle: Endlich und http://www.kreativ-depot.de/Werkzeug-Kleber/Klebstoffe/Heissklebepistolen-Klebesticks/Heissklebepistolen/Heissklebepistole-Mini-Klebepistole-110-240-V-20W.html#!prettyPhoto 11 Storing & Conveying 3. Solid Gear ● Barrel melting facilities mostly for series manufacturing Heated hose ● Melting of solid adhesive ● Pressure sensitive adhesives usually Actuator come on rolls (see left figure) Heated plate Barrel press with heated plate Quelle: Endlich und http://www.jk-tesa-shop.de/tesa-Easy-Cut-57421 Original container 12 Storing & Conveying  Small batch series manufacturing ● Advantage:  Low investments ● Disadvantages:  Manuell filling of stocking container  Risk of air entrapment  No processing of air-sensitive or high viscous adhesives Quelle: Endlich 13 Storing & Conveying  Big batch size manufacturing ● Advantages:  High amount of adhesives necessary (higher level of automation)  Processing of almost all types of adhesives possible ● Disadvantages:  High cleaning expenses when changing adhesive  High investment Quelle: Endlich 14 Agenda  Introduction  Storing, Conveying  Mixing  Dosing, Application  Joining, Fixation  Curing, Handling 15 Mixing  Mixing of adhesives most frequently necessary for multicomponent adhesives  As soon as the chemical counterparts get together the chemical curing process is initiatied  It is important to meet the pot time (the time from mixing the components till the end of processability)  Pot time can be extended by cooling  Three major types of mixing: 1. Batchwise mixing 2. Static mixing 3. Dynamic mixing Quelle: Endlich 16 Mixing 1. Batchwise mixing ● Mostly for manual processing with small batch size because: – Usage is rare – Necessary amount is small (e.g. SMD-bondings) – Mobile mixing solutions are required (e.g. at construction sites) ● Mixing in single-use cups (see figure) Quelle: Endlich 17 Mixing 1. Batchwise mixing ● Correct mixing ratio is essential (otherwise, final strenght of bond cannot be reached)  Components of adhesives are supplied in cartridges (see figure) ● Mixed in air can be a problem  Solution: Vacuum batch mixer (see figure) ● Disadvantages: – Manpower requirements – Personal protection due to possibility of dangerous materials Quelle: Endlich – Possibility of human failure (Wrong mixing ratio) 18 Mixing 2. Static Mixing ● Fixed (static) mixing elements (usually mixer nozzles) ● Laminar liquid flows are pressurised and twisted ● Prinicple: Every mixing element splits the liquid stream  contrarian parallel or radial rotation induces mixing „Layer “-formula: s=2n (s: Number of layers; n: number of mixing elements) Example : n=3  s=23=8 (see figure) Mixing nozzle with parallel splitting of streams Quelle: Endlich 19 Mixing 2. Static Mixing ● Static mixing nozzles create a drop in pressure  Compensation with conveying pump necessary ● Calculation: (fs: Mixing factor; : Viscosity; v: Volume flow; D: inside diameter of mixing nozzle; n: number of mixing elements) One-time mixing nozzle • Mostly for 2CAdhesives Quelle: Endlich und Habenicht 20