Can we fix it -- yes we can

Apr 06, 2011 By Ken Mingard
Figure 1: 1st Operation: Step 1: Blank and draw, 2nd Operation: Step 2: Redraw to final diameter; Step 3: Iron Wall Step; Step 4: Base shaping

Scientists at the National Physical Laboratory (NPL), the UK's National Measurement Institute are working on a project to develop a new, lighter weight beverage can punch with improved wear resistance. The target reduction of a can wall thickness of only 1 micrometre (0.001 mm) could save up to 800 tonnes of aluminium a year.

There are over 260 billion beverage cans being produced every year worldwide, with Europe being one of the biggest markets and growing at approximately 10% per year. The United Kingdom is the one of the leading markets with over 8.2 billion (steel and aluminium) cans being produced with 70% used for and 21% for .

How cans are made

A single production line can make up to 500 million cans every year from coils of aluminium or steel. The main procedure to form the body of the can is done in one continuous punch stroke by a 'Bodymaker' in about one fifth of a second. It is this Bodymaker punch which is the principle target for weight saving and its operation is shown in Figure 1. Firstly a shallow the cup formed from the aluminium sheet is drawn through a die to produce the can diameter (Figure 1, Step 2) and then the can walls are thinned and stretched through a series of ironing operations (Figure 1, Step 3). In the last step, the punch presses the base of the can body against a metal dome, giving the bottom of the can its inward bulge (Figure 1, Step 4).

The Bodymaker punch is made from a extremely heavy hardmetal alloy to withstand high forces and conditions which would wear away most metals very quickly. However, the punch weight causes problems of and alignment because of the speed with which it has to move and the tolerances needed to keep the correct can dimensions of only ± 0.002 mm mean that the punches still need to be removed regularly for maintenance.

How the process can be improved

If the punch density can be reduced while maintaining or improving its wear resistance and stiffness then large savings in energy, raw materials and maintenance time can be made. Working with the manufacturers of the punches and the beverage can manufacturer (in a programme funded by the Technology Strategy Board), NPL has investigated how Bodymaker punches wear and how new materials with lower densities might behave when made into new lighter weight punches.

Using state-of-the-art electron microscopy techniques, including Electron Backscatter Diffraction and 3D imaging, the ways in which different hardmetal alloys wear away has been investigated. It has been found that at the simplest level the basic wear mechanism can be understood using a scratch testing method developed at NPL. This simulates the action of a single abrasive particle being rubbed over the surface of the punch using a sharp diamond point at the end of a finely balanced arm.

This does not, however, test materials in the same environment which the punches experience, so NPL has developed a novel test system that simulates the combination of high stress sliding contact and impact that is found in during can forming. The changes in friction as aluminium is worn away by the movement of two test pieces of punch material is monitored over 100,000 cycles and the mass of material worn away from the punch material is recorded. Although this loss of material is less than 1/1000th of a gram, the differences in mass loss between different grades of material can still show which grade has better wear resistance and the volume of material worn away, less than a few thousandths of a millimetre in depth, can be measured by 3D microscopy as shown in Figure 2:

Can we fix it - yes we can

Explore further: Fiber-optic microscope will help physicians detect cancer, diseases at early stages

add to favorites email to friend print save as pdf

Related Stories

Hybrid welding process developed

Dec 18, 2006

U.S. scientists say they've developed a hybrid process involving the use of a laser in friction-stir welding to extend the application to more materials.

Rough times: NIST's new approach to surface profiling

Jan 09, 2008

Researchers at the National Institute of Standards and Technology have developed a novel technique for measuring the roughness of surfaces that is casting doubt on the accuracy of current procedures. Their ...


Dec 15, 2004

Researchers at the University of Leeds have developed a new type of hip prosthesis that they claim offers improved durability and longer life than current models in use today. In the effort to minimize material wear, the ...

Measuring the electrical properties of nano-crystals

Oct 20, 2010

The UK's National Physical Laboratory (NPL) is working to provide more reliable measurement of the electrical properties of materials used in nanotechnology – which could lead to much more accurate devices in the future.

Electromagnetic fields as cutting tools

Dec 01, 2009

( -- The bodywork on motor vehicles must be sufficiently stable, but processing the high-strength steels involved -- for example punching holes in them -- can prove something of a challenge. A new steel-cutting ...

Recommended for you

Smart sensor technology to combat indoor air pollution

Apr 14, 2014

Indoor air quality (IAQ) influences the health and well-being of people but for the last 20 years there has been a growing concern about pollutants in closed environments, the difficulty in identifying them ...

Drones used to assess damage after disasters

Apr 11, 2014

Researchers of the University of Twente use a new method to map structural damage after disasters. A remote-controlled drone with a regular high-quality camera takes a large amount of pictures of a building. ...

User comments : 0

More news stories

Intel reports lower 1Q net income, higher revenue

Intel's earnings fell in the first three months of the year amid a continued slump in the worldwide PC market, but revenue grew slightly because of solid demand for tablet processors and its data center services.

Low Vitamin D may not be a culprit in menopause symptoms

A new study from the Women's Health Initiative (WHI) shows no significant connection between vitamin D levels and menopause symptoms. The study was published online today in Menopause, the journal of The North American Menopa ...

Astronomers: 'Tilt-a-worlds' could harbor life

A fluctuating tilt in a planet's orbit does not preclude the possibility of life, according to new research by astronomers at the University of Washington, Utah's Weber State University and NASA. In fact, ...