Manual assembly systems

The manual assembly systems are divided into two main categories, manual single-station assemblies and assembly lines. 

Description of Manual Assembly Systems and Their Components... 

The components for the basic parts and the assembly parts are the substantial constituents of manual assembly systems. The assembly parts are often supplied in grab containers. The distances to be covered by the workers arms should be short and in the same direction. The intention is to shorten the cycle time and reduce the physical strain on the workers. This can be realized by arranging the grab containers in paternoster or on rotation plates. Further important criteria are glare-free lighting and adapted devices such as footrests or work chairs (Lotter and SchiUing 1994). 

When assembly at a workstation is impossible for technological or economical reasons, the assembly can be carried out with several chained manual assembly stations (Lotter 1992). Manual assembly systems consist of a multiplicity of components, as shown in Figure 20. The stations are chained by double-belt conveyors or transport rollers. The modules rest on carriers with adapted devices for fixing the modules. The carriers form a defined interface between the module and the... 

Figure 20 Components of Manual Assembly Systems. (Source Teamtechnik)...

The following criteria have to be considered in designing manual assembly systems. 

While the market needs were met with a high batch size of standardized products a few years ago, the current assembly and production lines have to be flexible and agile in order to satisfy the requirements of customers. Due to these requirements, optimized manual assembly systems have become an alternative to automated production systems (Feldmann and Junker 2003). Nowadays, around half of companies use some kind of automation of assembly (Butala et al. 2002). 

The intent in this chapter is not to present in great detail the mathematics behind the statistical methods discussed. An excellent reference manual assembled by the Automotive Industry Action Group (AIAG), Fundamental Statistical Process Control, details process control systems, variation, action on special or common causes, process control and capability, process improvement, control charting, and benefits derived from using each of these tools. Reprinted with permission from the Fundamental Statistacal Process Control Reference Manual (Chrysler, Ford, General Motors Supplier uality Requirements Task Force , Measurement Systems Analysis, MSA Second Edition, 1995, ASQC Press. 

Flex-link systems also allow a different level of automation at each of the assembly stations. Depending on the respective assembly tasks, the automation level can be stipulated according to technical and economic factors. In addition, step-by-step automation of the assembly system is possible because individual manual assembly equipment can still be replaced by automatic assembly station later on. 

A large number of analytical models have been developed for planning manual and general assembly systems. Another objective has been to measure and evaluate the performance and productivity of assembly system design by applying simulation. Two essential technologies are expleiined in this... 

Fiberoptic cables are currently assembled almost completely manually. Semiautomatic devices are available on the market for the premanufacturing process. After this process is completed, the ceramic ferrule of the connector is filled with glue, then the glass fiber is introduced into the ferrule hole. This assembly sequence is executed only manually at present. However, because no measuring systems are available for this purpose, manual assembly cannot ensure that the critical joining force will not be exceeded. If this happens, the fiber wftl break off. The fiber will be damaged and the connector win become waste. 

Diagnosis includes the entire process cheiin of feiilure detection, determination of the cause of failure, and proposal and execution of measures for fault recovery. ReaUzing and operating a high-performance diagnosis system requires comprehensive acquisition of the assembly data. For this purpose, three different sources of data entry in assembly systems can be used. First, machine data from controls can be automatically recorded. Second, for extended information, additional sensors based on various principles can be integrated into the assembly system. Third, the data can be input manually into the system by the operator. 

Due to the high investment cost in relation to the required flexibility, an increased interest is found on hybrid assembly systems where manual workplaces can be substituted by machines and vice versa (Bley et al. 2004). A further kind of hybrid systems allows humans and machines to work in the same workplace of the assembly (Kruger et al. 2009). Another trend can be observed regarding the increase of automation in the final steps of assembly (Hu et al. 2011). 

Manual Assembly Line Assembly systems in which all operations are carried out manually or that consist entirely of manual workstations (CIRP 2004). 

Semiautomated Assembly Line An assembly system made up from a combination of manual and automatic workstations. See Pig. 5 (CIRP 2004). 

The integration of manual workstations in automated assembly systems is necessary if (Lotter 1989) ... 

Hence, automatability allows for adapting the ratio of manual and automated work content in an assembly system. 

Move the Part for Placement Basically it is easy to bring the part to the correct placement position. But in the case of manual assembly of electronic circuit board, there are many similar positions where a part will fit. To guide positioning, there is normally a printed guide in the form of designation or numbering for each part on the circuit board. Additionally, a system where a light spot aids identification of the insertion position can be used. Then, the sequence of insertion tasks is predefined, the... 

Assembly/Disassembly Systems Most products consist of many parts, and their assembly requires considerable care and planning. There are three basic categories of assembly systems manual, high-speed automatic, and robotic (Kalpakjian and Schmid 2002). Manual systems are generally convenient for complex parts in small lots. High-speed automated systems use transfer mechanisms designed specifically for assembly. In robotic assembly systems, one or more robots can work at a single workstation or at a multi-station assembly system. 

One-piece-flow is a production process or a production principle in a production or assembly line, where an employee always transports one part from a station to the next station where it is processed. There are more stations than employees. The principle can be described most easily regarding the case of the manual assembly by an employee in a working system the... 

The manual systems that we have studied were using the movement of the operator s hand in order to realise the relative movement of the applicator and the parts to be coated. In the following application techniques, the parts to be coated move under the application system which has a fixed position. It may be rolls, die, fixed guns, doctor blade, etc. Usually the bonding operation is part of the total production line, and the adhesive applicator is integrated into a conveyor together with drying ovens, assembly system and presses. 

The only manual process in this system is adjustment of the reflow profile based on the results of soldering an assembly. The last step in the process would be to test the finished prototype board. This system could also be used for very small volume production runs, and aU components as described are available. With a change from milled boards to etched boards, the system can be used as a flexible assembly system. 

Figure 9.12 Structural bonding application for a reinforced plastic bumper assembly for a truck. The equipment dispenses a two-component structural adhesive onto the bumper assembly before it is integrated into the truck. In production, this is typically done robotically with a manual backup system (shown). The system being used is a See-Ro 488 meter/mix system the dispense gun in the picture is model 2200-250-000 dual-spool Snuf-Bak dispense valve that utilizes a No-Rush disposable static mixer nozzle. (Photo provided by Sealant Equipment and Engineering, Inc.)...

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