Text 4 a. Laser Revolutionizes Axle Design

The laser beam welding is used for joining components that need to be joined with high welding speeds, thin and small weld seams and low thermal distortion. The high welding speeds, excellent automatic operation and the possibility to control the quality online during the process make the laser welding an advanced joining method in welding complete car bodies in automobile construction.

1. A design and manufacturing revolution is taking place at an axle design and manufacturing facility in Italy. Just in production for Volvo and Iveco is a remarkable rear axle for heavy duty applications on which all but four of the normal 42 bolts have been replaced by laser welding or one-piece castings. The design is 13kg lighter than its equivalent predecessor, uses only two thirds of the amount of oil -a €25 saving for OEMs in lubricant costs alone - and has reduced parasitic losses. And there's more to come including a 'smart lubrication' system that will cut splash losses even further.

Fig.4

2. The new axle - called the 17X - results from a €20 million investment by Arvin Meritorin the Meritor HVS facility at Cameri between Milan and Turin. It has been designed for 44 ton-plus applications using engines delivering up to 560 hp and 2500 Nm of torque. Laser welding was the 'starting point' for the differential case design. Bolts eliminated include: ring gear to differential case (16); diff case to diff case (12); and pinion housing to carrier casting (10). The four remaining bolts are for the differential side gear bearing cover. The joining process is highly automated, at speeds of up to 1.5m/min, and involves autogenous welding where two components of the same metal are joined without the use of a sacrificial filler metal. This results in a very high quality joint with a smooth inside surface.

Fig.5

3. Laser welding has made the gear and differential case a single, exceptionally stiff, one-piece component. As a result, gears stay in mesh better, leading to longer life. It has even allowed designers to change the geometry, reducing the hypoid offset so that there is less sliding contact and, therefore, a higher efficiency. Interior axle surfaces are smooth, without ribbing, minimizing splash losses. This was made possible by the use of novel OptiStruct software that optimizes material distribution in accordance with the position of operational stress levels.

4. The axle also incorporates some interesting design features that bring its compatibility with current and future braking and chassis control strategies. An energy saving solenoid-driven electromechanical differential lock replaces the pneumatic system along with the associated valves and pipework. It can be automated from the ABS and ASR and should be available within one or two years. ( 2100 characters)

Exercise 5. Match the right and the left items. Use the key words in your answers.

1	What changes have been introduced into the rear axle design?	a	smooth without ribbing
2	What weight savings are brought by the new rear axle design?	b	a single, stiff, one-piece component
3	What vehicle was a new axle designed for ?	c	13 kg lighter than its predecessor
4	What kind of welding was applied in a new axle design?	d	autogenous welding
5	What is the specific feature of autogenous welding?	e	compatibility with current and future braking and chassis control strategies
6	What does the laser welding result in ?	f	44 ton-plus applications using engines delivering up to 560hp
7	What is the quality of the interior axle surfaces?	g	bolts were replaced by joints
8	What is the new axle design advantage?	h	higher car efficiency
9	What are the benefits of laser welding in car design?	i	two components of the same metal are joined without the use of a sacrificial filler metal

1	2	3	4	5	6	7	8	9

Exercise 6. Complete the sentences. Match the left and the right items and arrange them logically according to the text.

1	The amount of lubricant	a	has been reduced by one third
2	The axle construction	b	are joined without the use of a sacrificial filler metal .
3	Bolts in rear axle	c	are smooth without ribbing.
4.	The joining process	d	have been replaced by laser welding.
5.	The metal components	e	took place in Italy.
6.	Application of autogenous welding	f	is lighter than its equivalent predecessor.
7.	Interior axle surfaces	g	results in a very high quality joint .
8.	The axle design and manufacturing	h	is highly automated.

1	2	3	4	5	6	7	8

Exercise 7. Read the following text and summarize the advantages of laser welding. Make a short report.

Recently many manufacturing engineers have discussed the technical advantages of using lasers in place of more conventional techniques. The advantages of using lasers in comparison with the most popular techniques are shown in table1.

Table 1. Advantages of laser welding compared to other processes

Competing Process	Advantages of Laser Welding
Gas Metal Arc	faster welding rates by an order of magnitude; low distortion; no filler metal required; single-pass two-side welding
Submerged Arc	faster welding rates; low distortion; no flux or filler needed
Resistance Welding	non-contact, eliminating any debris buildup; can reach otherwise inaccessible locations; faster welding rates
Electron Beam	does not need to be performed in a vacuum; on-line processing; shorter cycles and higher uptimes; welds magnetic materials; does not require radiation shielding

Laser welding is also being applied in the production of partial penetration welds, for example, in hem flanges often used in doors, bonnets, boot lids and other closures . Although the majority of work performed has been on steel sheet, there have been a number of programs conducted on aluminum alloys. 

 The laser welding of aluminum alloys is more difficult than for steel, due to the high reflectivity and thermal conductivity of the material, the low viscosity of liquid aluminum and the tendency for cracking and porosity in welds in certain alloys. Extensive work over the past 10 years has demonstrated the feasibility of laser welding of aluminum alloys using CO₂ and Nd:YAG lasers, where once a threshold power density is exceeded for a particular alloy, keyhole welding can be established and seam welds can be produced with similar welding speeds to steel sheets. (1750 characters )

Exercise 8. Read the following text and name the benefits of the new door ring.