Guidelines for tube laser cutting

General

There is a difference between steel, stainless steel and aluminum square and rectangular tubes in the delivery specifications. This difference is caused by the different shape cross-sections, see images below. 

Steel and stainless steel

Aluminum

Steel and stainless steel
For steel and stainless steel ducts (square and rectangular), the angles should be drawn as follows:

• outside radius = 2x wall thickness (The value '2' is an average value of the size of the radii mentioned in the standards). 

• inner radius = 1x wall thickness. 

Aluminum
For aluminium tubes (square and rectangular), the angles should be drawn as follows:

• outside radius = 0.6 mm radius (acute angle).

• inner radius = 0 mm radius (acute angle).

• Aluminum(tube): up to and including 6 mm

• Steel: up to and including 12 mm

• Stainless Steel: up to and including 6 mm

• Tube diameter round: minimum Ø12.0 mm and maximum Ø254,0 mm.

• Duct: minimum square 12x12 mm and maximum 200x200 mm.

Maximum weight of the product per metre: 40 kg. Maximum length to be laser cut from one piece: 7,800 mm. In the case of machining or holes, a minimum size of 0.7 x material thickness is required. This is to ensure the cutting quality.

Tolerances

Refer to NEN-EN-ISO 9013 standard for tolerances for the cutting contour, the centring of the cutting contour and the overall length. . The tolerance is strongly influenced by a number of factors, such as:

• The form and dimension tolerance on the tube and duct
  These are described in the relevant standard sheets (for example EN10219). Deviations from the nominal tube/duct dimension have a direct influence on the centring of the cut contours.
• The dimensions and rigidity of the tube and duct
  Small and narrow ducts are flexible and move a lot in the machine during laser cutting. This can cause deviations in the dimensions and cutting patterns.
• Heat-input through contours
  When many contours are cut into a tube or contour, this gives a lot of heat-input and the tolerances can deviate. This also causes discoloration of the material.

Welding seam position

When loading the machine, the ducts are loaded randomly (sometimes a complete bundle). This makes it possible that the welding seam can be on different sides of the same product. If you want to determine the position of the welds yourself, please contact us.

Within 12 hours after placing the order, we would like to receive a PDF drawing on which the position of the weld seam and the corresponding position no. of the article are clearly stated. You can send this PDF to service@247tailorsteel.com.

With rectangular ducts, there are 2 possibilities of where the sealing joint can be, either on the short or long sides. We do not know where the joint is beforehand, so it is important to indicate the position of the sealing joint on both sides of rectangular ducts.

Example - The purple arrow represents the position of the weld seam

Splash on the inside of the tube/duct

The liquid material that forms during laser cutting can attach on the inside of the opposite side; this is also referred to as splash. The dimension of the splash depends on a number of factors:

• Internal diameter of the tube/duct
  The larger the diameter, the smaller the splash.

• Wall thickness of the tube/duct
  The larger the wall thickness, the bigger the splash.

• Internal surface of the tube/duct
  A smooth - greasy tube/duct is less sensitive to the attachment of a splash than a rough - dry tube/duct.

Splash is not removed by 247TailorSteel. You can do this yourself in post-processing.

Engraving

247TailorSteel only engraves functionally, for positioning or identification. Blind holes are automatically recognized as engraving. If desired, Sophia® can convert a cutting contour into an engraving*.

• Draw outlines to be engraved in yellow.
• Engraving/cutting lines should not touch or intersect.

Way of drawing engraving

2.5D-laser cutting

247TailorSteel cuts 2.5D. This means that the cutting edge is perpendicular to the material (centre-orientation). The software of 247TailorSteel converts 3D-cutting edges into 2.5D cutting edges. This means that a product can be cut different to the drawing. See the examples below for an impression:

3D laser cutting

2.5D cut holes in round tube

Holes in round tubes are cut at right angles to the material (centre point). As a result, the holes are cut differently than drawn. Holes that are drawn cylindrically (blue lines in the image) are cut elliptically (orange lines in the image). The diameter of the round hole, measured on the inside diameter of the round tube, corresponds with the diameter of the drawn hole. The diameter of the hole measured on the outside diameter of the tube is bigger and ellipse shaped. These holes are not suitable for, for example, wire tapping.

However, if you require that the hole is cut cylindrically, please inform us within 24 hours of placing the order and provide a clear PDF drawing that explicitly indicates which operations need to be cut cylindrically. 

ATTENTION: The diameter of cylindrical holes in round tubes has an upper limit and can not exceed approximately 0.5 x tube diameter.

A) the drawn shape
B) the shape as produced

2.5D-laser cutting in mitre

247TailorSteel cuts 2.5D. This means that the cutting edge is perpendicular to the material (centre-orientation). In case of products that are drawn in mitre, that leads to a groove being created in the outer corner (see images below). These grooves are often filled during welding.

A) the drawn shape
B) the shape as produced

Laser cutting of U-shaped products

U-profiles and segments cannot be cut with 247TailorSteel. In this instance, the system does not recognise a tube or duct. It is important that the full circumference of the tube is present somewhere in the drawing. One of the solutions for this is to draw a “ring” of the starting material alongside and to connect this with a small connection (see images). To this end, please note the available material. To this end, look at the “material summary for tube/duct”. The solutions referred to can also be applied to round tubes. If indicated by the Customer, the additional “ring” and/or the “bridge” can be omitted during laser cutting in many cases.

In addition, there is the option of choosing to draw an additional “bridge” to get the required full circumference (see image).

Connections of tubes

Connections of tubes frequently give problems when drawn in 3D. The online tool, Sophia®, does not always convert the cutting lines correctly, so that the mutual connection of the tubes is not “seamless”. In some cases, this can be solved internally, but new drawings are usually requested. Look at the example below of a 3D-drawing with the products as a result and an example of a tube connection drawn fully in 2.5D.

Please note: Every order is unique to us. It is therefore also important that, even in case of recurrent products, the specifications, such as the position of the welding seam or the engraving, are again indicated.

Example - 3D drawing

Example - 2.5D drawing

Method of drawing

When machining close to the wall thickness, it is important that the machining is at least 0.1 mm from the wall thickness. (see picture) 

Example - Minimum distance for an operation

When any machining is done near the radius/wall thickness, it is important that it is at least 0.1mm from this. 

The following drawing method requires us to make additional cuts during the process, which may affect the cutting quality. To avoid this, it is recommended to draw the corresponding machining as follows. (see picture)   

Way of drawing radius in square tubes

Blind rivet nuts

Our new tube laser cutting machines are equipped with a new technology for fitting blind rivet nuts in tubes.

• Material blind rivet nut: stainless steel and galvanised steel;
• Only possible in square or rectangular tubes up to 150x150 mm;
• Only one type of blind rivet nut per order;
• Flange must not exceed radius (see below);

The table below shows at which wall thickness which type of blind rivet nut can be fitted:

ER:

Only available in galvanised steel.

FTTE:

Available in galvanised and stainless steel.

Hole size

Minimum tube size

Blind rivet nut on one side

Blind rivet nuts in opposite sides

Blind rivet nuts in adjacent sides (when placed in the middle of the side)

Position of flange / position of blind rivet on tube

Changelog