Joinability of different thermoplastic polymers with aluminium AA6082 sheets by mechanical clinching

The International Journal of Advanced Manufacturing Technology - The joinability of different rigid thermoplastic polymers with aluminium AA6082-T6 alloy sheets by mechanical clinching is...     

Parametric study on mechanical clinching process for joining aluminum alloy and high-strength steel sheets

The purpose of this study is to investigate the effects of process parameters on the joint characteristics of advanced high-strength steel DP780 and Al5052 alloy sheet in mechanical clinching process. The defects in the clinching joint, such as necking of the upper sheet, cracks in the lower sheet, and no interlocking, occur because of the different ductility between advanced high-strength steel and aluminum alloy. In this study, the effect of the process parameters of the clinching process on the joinability of advanced high-strength steel with Al5052 alloy was investigated using finite element (FE) analysis. From the result, the die radius, die depth, and die groove shape were mainly affected by the joinability of advanced high-strength steel with Al5052 alloy. H-type tension test was performed under the same condition as the FE analysis. In addition, the joint strength was determined by interlocking length as well as neck thickness.     

Joining STS304l sheets by using nano-adhesives

This study introduces a new nano-adhesive which is an improvement over the conventional epoxy resin that is widely used in the automobile industry. Multi-walled carbon nanotubes (CNTs) (1% to 4% by weight) were mixed into the epoxy resin by using a mixer. The bubbles generated during mixing were removed by using a high vacuum. The electrical and mechanical properties of the joints were assessed by considering the geometric parameters of the nano-adhesive bonded joints to optimize quality and performance for actual application. The results show that the electrical resistance of nano-adhesives decreased with increased CNT weight percentage and decreased thickness of the bonded layer. Static tensile strength increased dramatically at a CNT weight percentage of 2% compared with other values. The surface treatment condition of the plates also affected the tensile strength of the nano-adhesive bonded joints.     

Joining sheets perpendicular to one other by sheet-bulk metal forming

This paper presents a variant of the traditional ‘mortise-and-tenon’ joint, which has been used for thousands of years by carpenters and blacksmiths to connect wood or metal parts. The new proposed joint is utilized to fix longitudinally in position two metal sheets (or plates) perpendicular to one other by sheet-bulk metal forming, at room temperature. The development is performed by means of a combined finite element and experimental investigation focused on the identification of the major process parameters and on the understanding of their influence on the overall joining feasibility. Destructive testing is carried out to characterize the performance of the new proposed joint, and an analytical expression is provided to determine the maximum tensile force that the joint can safely withstand.     

Joining process for copper and aluminum tubes by rotary swaging method

Connection technique of copper and aluminum is a key challenge in refrigeration industry. In this paper, rotary swaging connection process is proposed to connect cooper tube and aluminum tube in physical way. We find the length of overlapped area has a great effect on the joint reliability, and it should exceed the deformation region length. The joint strength is approximately determined by necking. With the reduction of the diameter at the necking area, joint strength first increases and then decreases. Some experiments are carried out to test the joining strength. It is shown that the joints are reliable enough, and joining by rotary swaging method is effective to combine copper and aluminum tubes.     

An experimental analysis of process parameters to manufacture metallic micro-channels by micro-milling

Miniaturisation of products is a current megatrend, and it presents a wider range of opportunities to expand manufacturing markets. Micro-device design and manufacturing is a growing area of scientific interest for large number of industrial fields. This paper reports the characterisation of micro-milling process to manufacture micro-channels in order to understand the behaviour of process parameters when a standard milling machine is used. This study is based on micro-channel manufacturing through a set of experiments varying parameters such as spindle speed (N), depth of cut per pass (a _p), depth (d), feed per tooth (fz) and coolant application. Materials used were aluminium and copper with a hardness of 21 HRB and 72 HRB copper, respectively. Results are obtained by evaluating dimensions, shape and surface finish of the micro-channel. The use of coolant in micro-milling is found to be a relevant factor to improve micro-channel-achieved dimensions and surface finish. In general, micro-channels in aluminium were found to achieve better quality than those in copper.     

Limit analysis on surface roughness and dimensional accuracy of spray metallic crust for rapid tooling production by metal arc spraying process

Repetitively prototyping several prototypes of the same component using currently available rapid-prototyping equipment can be very costly. Substantial savings can be attained with the use of a metal spray process to produce a crust shell on a rapid-prototyping pattern coated with mould release agent (PVA), and then backing the crust with aluminium granules so as to form rapid mould/tooling (RT). The smoothness of the innermost spray layer and its dimensional accuracy in relation to the RP prototype are factors that ensure good quality of parts replicated by RT. This paper establishes a preliminary model for predicting the upper bound of the former and the lower bound of the latter, which have been experimentally verified by arc spraying zinc onto PVA. The theoretical model permits the prediction of spraying parameters for controlling the achievable surface finishing and dimensional accuracy of a spray in RT production.     

Fabrication of micro spur gears by step powder extrusion of Zn-22wt%Al powder without sintering process

Micro spur gears were fabricated using the LIGA process and step powder extrusion without sintering. It is important to manufacture micro dies with high aspect ratios and determine the appropriate extrusion conditions for the micro-forming process. Micro-extrusion dies with close tolerance and long bearing length were produced by the LIGA process. Superplastic Zn-22wt%Al powders can deform under low stresses and exhibit a good micro-formability (average strain rate: 10^?3s^?1; constant temperature: 250°C). These powders were compacted to a cylinder (diameter: 3 mm; height: 10 mm) under 10kN compressive force, and sintered at 350°C for two hours. Micro spur gear shafts were not produced upon extrusion because of the high working pressure on the die surface. For the reduction of the forming load, step powder extrusion was carried out on the compacted powder without a sintering process, but controlling the temperature dwelling period. This process has succeeded in fabricating micro-gear shafts.     

Effects of different metals on adhesive wear behaviour of alloy surface produced by TIG process

Abstract

Low carbon steel surfaces were alloyed with composite powders using the tungsten inert gas welding method. After the alloying process, the effects of cladding surface on the microstructural characteristics and adhesive wear of the alloyed samples were examined. The sliding wear behavior of samples was investigated in a block on ring apparatus under the loads of 20, 40, 60 and 80 N respectively. In the experimental investigation, a low carbon steel surface was alloyed with austenitic stainless steel powder and austenitic stainless steel powder mixed with 4·5% Co, Mo and Ti particles respectively. Following surface alloying, conventional characterisation techniques, such as optical microscopy, scanning electron microscopy, energy dispersive spectrograph and X-ray diffraction, were used to study the microstructure of the alloyed zone. Examination of the microstructure revealed the presence of M₂₃C₆ carbides, solid melt phases and intermetallic phases, such as Ni₃Ti, depending on the alloying element in the composite. As the amount of the reinforcing material increased, the saturation rates for the samples decreased, while their hardness increased. The adhesive abrasion tests conducted revealed that temperature input plays a significant role on the microstructure characteristics, which positively affected the adhesive abrasion values of the samples. Consequently, the tungsten inert gas welding method was successfully used for the surface alloying of low carbon steels.