Andrea Bustreo is a product engineer in the R&D department at Gasparini Industries. Click image to enlargeby Andrea Bustreo

How to avoid scratches and dents when forming stainless steel

Stainless steel is a wonderful material. Shiny, resistant, durable. But it’s also expensive, difficult to bend, and easy to scratch. When working with pieces that will be used as cladding, home appliances, and furniture, even a small scratch becomes a big problem. How can you cut and bend stainless steel without damage?

Shearing is often the first critical point. A bench equipped with plastic ball transfers, that let sheet metal to slide freely, is highly recommended. When the blank is cut, it has to be pressed against the bench to hold it in place. This system has a downside: pressure against balls leaves dents. Top manufacturers provide an anti-scratch system, with ball transfers mounted on a pneumatic support, that lets them disappear below the resting surface.

PTools must always be oiled to reduce friction and kept clean from materials that can scratch the surface.Click image to enlargeressure of blank holders must also be adjustable. Smaller and thinner pieces require a lower force, as cylinders will leave marks on the surface. Quality machines are equipped with a CNC able to vary the applied force through an independent hydraulic circuit. Also, cylinder feet must be capped with anti-scratch plastic material. Nylon is typically used because of its low coefficient of friction. Pistons must also be absolutely tight to avoid oil or grease leaks that might stain the sheet.

Hold-down cylinders. Cylinder feet must be capped with anti-scratch plastic material.Click image to enlargeAfter shearing, forming comes into play. Most frequent cosmetic damages in this phase are due to sheet metal scraping against the die edges. To limit this problem, you have to use special dies, with a bigger edge radius. Another more expensive solution is to use dies with rollers. Small cylinders are embedded at the edges of the die opening. These pins can rotate, reducing friction and scraping. This type of tools must be kept particularly clean so that dirt does not block the rollers. Specific protective plastic films can be applied to the die to limit scratching, but they may also lead to lower accuracy.

It’s also important to choose a punch/die pair suitable to the sheet metal, its thickness and the desired angle. High strength steels have a bigger bending radius and need a bigger die opening, otherwise it could crack on the outer edge, damaging both the aspect and the resistance. Tools must always be oiled to reduce friction, and kept clean from debris, dust, dirt, rust, chips and other material that can scratch the surface.

Front supports equipped with ball transfers, seen here, support metal sheets to prevent them from curving due to their weight.Click image to enlargeStainless steel sheets are often large and thin. If they are not properly supported during forming, they curve under their own weight making the so-called “counterbend” around the die. Sheet followers solve this problem. They are front supports equipped with ball transfers that, during the bending phase and when the ram is raised, support the sheet. As well as rotating, they have to shift because the centre of rotation is not fixed. Top quality press brakes are equipped with retractable supports next to back gauges. In certain cases, sheet followers can be mounted also in the inner side of the pressbrake. These accessories support the sheet while it’s resting against the back gauges, avoiding deformation. SMT

Andrea Bustreo is a product engineer in the R&D department at Gasparini Industries.

 

Shaping up

by Tim Wilson

Canada's die and mould industry is on an upswing

Watch your language

by Mary Scianna

People working in English dominant countries like Canada and the US take language for granted.

Designing homes with steel

A visual tour of 42 beautifully designed homes constructed with structural steel.

Time lapse barge fabrication

This time lapse video shows the fabrication of an ATB Tank Barge by Harvest at Vigor in Portland, Oregon.

The thinking robot

In the 2015 British science fiction thriller Ex Machina, a programmer who works for the world’s most popular search engine is asked by the company’s eccentric CEO to administer the Turing test to a humanoid robot he has created, called Ava.

Reshoring: Home for the holidays or home for good?

By Mary Scianna

There’s a saying that it takes a village to raise a child.

CANWELD 2017

Canada’s premier annual event for welding, metal fabricating and finishing 

NASA tests 3D-printed rocket part

NASA has successfully hot-fire tested a 3D-printed combustion chamber for a rocket engine. This is the latest in a long series of 3D-printed rocket components that NASA has worked on over the years at its Marshall Space Flight Center.

Gearing up for business

Opportunities for growth in resilient automotive industry 

by Tim Wilson

If there is a good news story in the midst of the present economic malaise–in which the US economy is stuck in neutral, and the European crisis trudges on–it is here in Canada where, despite a strong dollar, the automotive industry has shown remarkable resilience.

Industry stats point to a manufacturing revival

81% jump in Canadian machine tool orders; record breaking attendance at fabricating show

By Shop MT staff

While uncertainty continues to hover over the global economy, North America’s manufacturing sector seems to be bucking the trend with the latest industry figures pointing to a strong rebound.

Managing the Economic Pendulum

Managing a manufacturing business in Canada has its challenges,

Is a tandem press brake the right solution for you?

This video highlights the benefits of using a tandem press brake (two press brakes used in a single operation) versus purchasing one large press brake. It examines installation costs, productivity and versatility between the two machines.

Cutting Tools Tech Tips: A Simple Hack to Improve Shop Profitability

by Jim O’Leary

Don’t overlook important elements to optimize machine tool efficiencies

Simulating Five

No matter how easy to operate, few would argue that five axis machining centres are more prone to tool and fixture interference than those limited to three axis work.

Stay In Touch

twitter facebook linkedIn