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During the construction of metal buildings or steel structural buildings, we always use steel purlin! Among the popular c and z steel purlins, we may have questions about which one to use. Therefore, regarding this, we will give some brief introduction in the article.

Steel purlin is necessary elements for steel architecture, steel structural engineering, or steel building. Furthermore, steel purlin is not applied for buildings only, but also many other infrastructure projects. This makes steel purlin roll forming machine a very important roll forming equipment.

The common steel purlins in the market are like C purlins, Z purlins, U purlins, Sigma purlins and so on. Possibly some people call them C channels, z channels, u channels, sigma channels and unistrut channels etc. These steel purlins or steel channels have been manufactured by roll forming machines out of galvanized steel, cold rolled steel or mild steel.

Firstly,  a purlin is a horizontal beam or bar used for structural suppport in buildings, most commonly in a roof.  Several kinds of purlins exist. People like to divide them into categories based on their material and shape.  The purlin most commonly used in roofing is the steel purlin. Nowadays, we produce  “C” and “Z” (Cee and Zed) shaped channels via c purlin roll forming machine and z purlin roll forming machine from high-strength zinc-alloy coated steel with minimum yield stress 60% higher than the respective profiles formed through hot forming.  This means that we can use sections of minimum thickness and weight, resulting in reduction of the time and the cost of the construction.

And then, people tend to use C and Z steel purlins on their steel framed buildings, in order to provide an efficient, lightweight and cost efficient roofing, cladding and walling support system (Purling and girt system).

However, there is always a question: Shall I use C steel purlins or Z steel purlins on my building? Is there any other difference only except for the shapes?

As a result, let’s take a look into the mysteries of the choosing between C and Z steel purlins.

A standard purlin, is a horizontal beam along the length of roof, resting on principles and supporting the common rafters and sheets. In steel construction projects, the term Purlin typically refers to roof frame members that span parallel to the building  ridge, and support the roof sheet or steel deck.  Metal building system commonly use C Purlin, and sometimes Z Purlin to allow flexural continuity between span.

However,  steel purlins may work better than other elements in some infrastructure projects than just buildings. For example in photovoltaic projects, the c shaped channels, or known as unistrut channels, are the first choice for contractors. In highway projects, W shaped guard rails are the most important elements, and some people call them W purlins.

Standard sizes of the C and Z purlin or channel vary from 80mm to 300mm, and thickness from 1.5-3mm. Some other sizes or thickness are also available for special usage. The most common roll forming machine is the quick-change C/Z purlin roll forming machine that can make both C/Z steel purlins on one machine, but not at the same time. The C/Z STEEL PURLINS usually have punching holes on web or flanges. For some other owners, they prefer to run separate C Purlin roll forming machine and Z purlin roll forming machine to produce C and Z purlins at the same time.

Dimensions of C and Z Shaped Steel Purlins:

The “C” and “Z” shaped sections have  standard dimensions (Web height:80-300mm; Flange size: 50-80mm; Leg Size:15-30mm). You can have any cutting length from 1.000mm to 20.000mm according to the engineering design data.  The designed punching holes are also available with the following restriction:

• Minimum distance from the end section 35mm

• Minimum centre holes distance in perpendicular axe 65mm.

Z Shaped Profiles:

The “Z” shaped sections structural elements feature two flanges of different width! In this way, two elements with the same static height can overlap, fitting perfectly to each other.

As a result, we achieve to bridge multiple spans with continuous Z purlins.

C Shaped Profiles:

The “C” shaped sections structural elements feature two equally sized flanges and are ideal for structural support in walls and as floor joists in addition to roofs. Furthermore, we can use Cee also to form braces, ties or columns in sheds.

Applications of C and Z Shaped Section Channels:

Since the moment of inertia on Z purlin’s weak axis is much bigger than that of C purlin, Z purlin works much better from the integrity point of view.

Z steel purlins can be overlapped continuously while C steel purlins cannot, therefore, it’s better to use Z steel purlins instead of c purlins on metal buildings with continuous spans.

Z purlins are much stronger than C purlins due to its continuous or overlapping capability. In this case, for the metal building with bigger roofing loading capacity.

On the roofing of steel framed structures with single spans, and for supporting walls, it’s better to use Cee purlins because it’s easy to install and calculate. On wa the can work as supporting for roof, walls and floor etc.

For the metal buildings installed with concealed fixing or klip lok roof panels, Z purlins can work better than C purlins.

All the above information may help you to choose the right steel purlins for your buildings.

Types of different Steel Purlin Roll Forming Machine:

At the moment, we has developed series of Steel Purlin Forming Machine for different applications.

Traditional design: Manual adjust the spacers and replace the cutoff blade. The changeover time for sizes is around 3 hours.

Pre-Cutoff design: Manual adjust the spacers with no need to change the cutoff blade. The changeover time is around 2.5 hours, a little less than the traditional one. but the ends of the Purlins will be a bit deformed.

Quick-change design: The machine will change the web sizes and flange sizes automatically according to the sizes input on the control. Manual adjustment from C to Z shape, and manual change on universal cutoff die. The Changeover Time is only 2 minutes.


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