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The Right Tunnel Oven Belt Supplier

The Right Tunnel Oven Belt Supplier

Opening Thoughts - "The world is a village nowadays"

We have all heard an expression like this in recent times. This is a “less threatening” way of describing the term ‘Globalization’. Indeed globalization with all its pros and cons has found its way in many sectors and industries.
But how is it in the baking industry, when it comes to machinery and spare parts?

With tunnel ovens being bigger projects, usually sold and bought as turn-key projects, there is an internationally active top-ten of OEMs followed by another group of somewhat smaller producers, who focus with their strategy on specific areas of the globe.

The biscuit producer once he decided for an oven supplier, is in a way connected (or should I say depending?) to the OEM for the whole life time of the tunnel oven. Because of the volume of such turn-key-projects the OEMs usually can afford to have local agents. That makes for such complex projects life for the buyer easier.

But how is it for one of the most important components in such a tunnel oven, the baking oven belt? There are hardly any international quality standards like DIN / AISI / ASTM / AFNOR / BSS etc. that one can refer to and rely on.

Depending on the baked products, maintenance service, and general care, an oven belt needs to be replaced several times within the lifespan of the tunnel oven. Do the bakers know, for example, what type of belt they are using and where they can get it?  Or are they going to rely on the spare part services offered by the OEMs instead?

In general, there are not so many differences in the principal types of belts used in tunnel ovens. According to my experience, the OEMs rely very much on their “standard and established solutions” and are very hesitant towards, if not skeptic, of new, “more modern” developments. No wonder then, since when it comes to the “ins and outs” on belt technicalities it is the belt producer who should be the expert. The OEM and especially the end user for this component are in the majority of cases practically “interested laymen”, who have to trust and rely on the belt producer.

My experience in the field is that in many cases both OEMs and end-users stick to the original belt type for ages and are unwilling to leave their comfort zone, even if there are new technical developments or they need to solve a problem. However, whether on their own or together with the OEM, the biscuit manufacturer is recommended to look for the optimum oven belt and best supplier available.

But how to decide for the right belt supplier for the OEM and/or the end user? Just as there are “fly-by-night-traders” with a somewhat questionable reputation there are also belt producers, who will “play in the same league”. So, when it comes to the criteria for the right supplier, there are soft facts (supplier-related) and hard facts  (product-related) to be considered. Let’s start with the soft facts, not to be underestimated.


Through the internet, fairs and talks in the market one can compile a “collection” of possible suppliers comparatively easily.
Here are some thoughts of how to select the right one:

How is the general communication with this supplier? Do you have the feeling that the whole communication is pretty standardized or does he give you the individual treatment and responses to start a real and fair partnership?
What are the languages you can communicate in? English is certainly the international lingua franca and mostly used, but is there a willingness to appreciate that this language might not be your native one?

Questions from the supplier
Is the supplier asking questions to understand your situation or your potential problems better? A belt is only a part of a bigger construction but very important for smooth and satisfying operation. Its malfunctioning can cause a nightmare to the baking plant. So, when the possible belt supplier may ask questions like:
Who built the oven? How old is it? What type of oven heating?
What type of tracking and tensioning?
Which products are baked? Any special remarks or problems?”
This is actually a good sign, since the supplier seems to follow the philosophy

   “Only when you know where you come from, you know where to go”.

As stated before, the belt producer is or should be the expert and the end user is quite often the layman (something they cannot be blamed for). Consequently, technical points should be explained in an understandable way. You as the end user should not be “bombarded” with “tons of gobbledygook” (i.e. technical jargon) which is hardly understandable. You are not sure about the detailed characteristics of the belt you want to replace? The possible supplier is willing to check a sample piece and asks you to send him one before he prepares the offer, consider it as a sign of expertise and competence then. Another aspect, that I learned and followed in my professional career:               

“Business is not done between companies, but between people and best between friends”.

Your partners must not be anonymous but should give names and be willing to answer your questions and concerns.

Problem solver
If you do not only want a replacement belt but also have a problem, where you are asking for advice and the supplier is not just making an offer, but gives some information or suggestions for your problem, then consider it as a bonus for this supplier in your final choice.

Full range supplier
For the use in tunnel ovens there are only a few principal types of mesh belts in use. The following three resp. four are the most frequent ones:
(The solid steel belt with a very different production technique for selected baking application only has been excluded and is to be seen completely different)

A – round wire link belt & braided link belt as the ones with the least cost and easiest to produce
B - multiple spiral belt        as the one with the highest material fraction in production costs
C - rolled baking oven belt  as the one with the highest requirement to production skills needed

The principal belt types (clockwise): stix belt with braided links / cracker belt with multiple spirals / biscuit & cracker belt with flat rolled wires / bread belt with round spirals

The principal belt types (clockwise): stix belt with braided links / cracker belt with multiple spirals / biscuit & cracker belt with flat rolled wires / bread belt with round spirals

In some baking applications these belts are interchangeable and having a problem with one of these types, the change to another type of belt might bring the solution. So if your probable supplier is able to produce all of them then the chance that you get an unbiased technical comment is quite high. Around the globe you find many producers who are able to supply round wire and braided link belts (and just that), fewer produce the multiple spiral belts and only a handful rolled baking oven belts (aka Z-belts). And as far as I know there is only one company who produces all these main types.

So when you look for a belt supplier, try to get information about what range of belts they produce. If they only manufacture one type of belt there is a chance that this might be in the worst case a “production in a garage” only and possible technical comments as well as after-sales-service could be questionable.


Downloaded internet-information from a full range mesh belt supplier

Paperwork (Style)
In international communication between bakery and supplier you often struggle with three issues:

  • Time difference
  • Language insufficiencies when it comes to special technical or commercial terms (maybe both sides cannot use their native tongue)
  • Somewhat poor and difficult phone connections

Therefore, written communication becomes more important. Internet, cloud services and emails fortunately make this a whole lot easier these days. From my experience I prefer to describe written communication and paperwork as the “written sales discussion” of the supplier. As an example I present the offer eventually made to you as a possible belt buyer. As a purchaser you need to ask the following questions and replies to that should be found in the offer:

1.           What type of belt is offered?
2.           What is the technical specification for this belt (dimensions & quality)?
3.           What are the parameters in width and length?
4.           What is the price in which currency per unit and in total?
5.           What is, apart from the belt costs, included in the offer (packing, freight charges, insurance)?
6.           What is the delivery time?
7.           What is the means of transport?
8.           What are the payment terms?
9.           What is the legal frame for the offer?
10.         Are there comments & suggestions to my questions?
11.         Who is offering and who is supplying?



Example offer with all criteria

One will be surprised to see how often suppliers take their obligations too easy and do not pay enough attention. On my many trips in the market I have seen some, if I may say so, really “strange” written offers, having not much to do with the criteria of a complete offer.

From the general flow of communication and the response time one should get a fair impression about the supplier’s reliability and truthfulness. If that is not enough, a good supplier won’t mind giving references. In our sector quite a number of clients, however, don’t want to be cited as reference because of concerns with regard to fabrication know-how etc. But references from banks or chambers of commerce could be a source for confirming the supplier’s general reliability, too.

All good and reliable suppliers should have websites, which are not only “making a show” but give information about their company and their products, often with downloads for product information available.

In the past, with less possibilities of communication, the location of a probable supplier was of greatest importance. To be prepared for emergencies, the end user, above all, preferred nearby suppliers, maybe even from the same country and was willing to swallow one or the other bitter pill in the relation with them for that.
In today’s world of internet, email, cell phone systems, video conferences, WhatsApp, Hangout apps etc., dealing with a “far-away-supplier” is no longer an issue.

Being located in Germany, I once dealt with a production manager of a plant in North America, who by then insisted to work with local suppliers only who could be on-site during belt installation, so that “he was covered”. When he had to install the first belt from our company, a supplier 12 hours of flight away from his plant, he was surprised that:
              • we could be in continuous contact during installation process via phone and mobile apps;
              • we had no problems to accompany his installation process over the whole weekend at any time (despite a 9 hour time difference);
              • that the installation of this (for him) new belt type was eventually much easier than in the past.

So to have a nearby supplier is not a must anymore, you just can choose the best and most experienced.


Well, the hard facts are circling around the product itself and should be carefully specified and discharged.

Technical Information
Ensure that your supplier offers general technical information about the belt in the form of pamphlets, catalogues and/or data sheets, giving you the frame idea about what products they are able to produce.


Example of a downloaded belt product sheet

In most tunnel ovens belts in the mild steel quality are used if there are no “chemical requirements” like the use of salt etc. This type of steel proves to have a good response to the heating process in the oven and it is not “unnecessarily expensive”.
This quality seems at first sight simple and easy but it is not quite the case. 

Firstly, there are a number of different names and codes used for this steel quality like: commercial steel, RSt37-2, black steel, S235JR, 1.0038 or any other names based on American, British, French, Japanese standards. Even “fantasy names” are sometimes used. That can be confusing.

Secondly, coming from this great variety of different names with different standards there can be variations in the chemical analysis, although maybe only small. The number of alloying elements in the mild steel quality standards is small, but there are “good” and “bad” ones. These elements can influence the performance characteristics in both ways. What is good or what is bad for the belt quality is often part of the production know-how of the belt producer and stipulated with the raw material supplier. As a consequence no quality conscience belt producer is buying their raw material on the spot market but from long term continuous suppliers.

Thirdly, the quality of a belt should be as homogeneous as possible over the whole length, especially when it is a longer one. It is in the interest of the belt user that the belt has the same tensioning behavior, reaction to the oven’s temperature and the least possible width shrinkage anywhere along the whole belt lengths.

These are examples of “bad” wires with a rough surface, to which baking dirt can stick much easier

These are examples of “bad” wires with a rough surface, to which baking dirt can stick much easier

A good belt producer has the production know-how for all this. If in doubt, talk with your intended supplier about these quality aspects. He will certainly give you some information and even present you with belt samples, when of help.
If you then look at the wires through a magnifying glass and see cracks on the wire surface, these are indications for a high possibility for no good steel and wire quality.

Example of a homogenous, equal and rectangular belt mesh structure of high quality (a Z-belt F4015 in this case)

Example of a homogenous, equal and rectangular belt mesh structure of high quality (a Z-belt F4015 in this case)

There is one very simple basic set of facts about tunnel oven belts. The specification should always contain information about:

- the quality
- the crossbar diameter
- the spiral wire diameter
- the crossbar pitch
- the spiral wire pitch
- the edge design (looped or welded)
- the type of weaving or forming these wires to the intended mesh.


Quite often details to these points are missing in the description of the supplier’s specification. Sometimes the information about the belt’s weight per square or running meter is helpful, too to compare with others. Therefore ask and clarify, so that you can check!

This is a very delicate subject and one is skating very quickly on thin ice. Why?
The belt producers are paying for raw materials on weight basis but selling their belt with prices per running meter.
So a conflict becomes obvious => buying on weight and selling on a meter basis.

It is impossible to fabricate any steel wires without diameter tolerances and there are international standards for this, whether hot rolled or cold drawn, with plus & minus figures.
               When you know the standard you know these tolerances.
Also the crossbar and spiral pitch are subject to variations, depending on the usage degree of the forming tool.
               But there are no international standards for this.

Unfortunately there are some belt producers around the globe who are not really fair to their clients and tend to use mainly wires with minus tolerances and for the pitches, especially the spiral pitch, they “prefer” sometimes extensive tolerances on the plus side. As a consequence the mesh structure gets coarser and the belt gets lighter. Coarser mesh structure increases the risk that the baked product gets jammed and cannot be lifted off “as usual” by the transfer knife. Lighter weight means the belt gets weaker which might cause problems, since length elongation and width shrinkage will increase, the belt tensioning has to be adjusted more frequently and finally it will break earlier.

A last remark here: every time you see the abbreviation “abt.” with figures in the specification, please be aware that this means ´+/- 10%’ in accordance with international customs and practices.

And again, tolerances are usual and unavoidable, but they should be clear, understandable and reasonable.
⇒ Tolerances could be the deal-breaker for choosing your belt supplier!



This example of a website download shows supplier has nothing to hide: product photo, details and full technical data are given

Drawings & Sketches

“A picture is worth a thousand words”
This common phrase is applicable for better understanding the technical specification of (tunnel oven) belts, too. So ask your potential belt suppliers for drawings and/or sketches of the belt offered. Any reputable belt supplier should be able to give it.
Often they have something like this in the download section of their websites.



This downloaded specification sheet can even be used as a fill-in form by the clients to describe their needs

No Coding
If belt suppliers give coding only instead of clear figures for the belt specifications in their offers they are clearly too afraid of competition!
This might be a bit provocative - but it is true. It will be more difficult for the belt user to look for alternative suppliers and/or solutions. Samples or (scaled) pictures or in the “worst” case, the other supplier’s checking the existing belt on site are a way for solving this situation.
But no good and reputable supplier has to fear competition and hides behind non-explained codings.
Remember this when evaluating between different offers!

Good and appropriate packing of your belt is indisputable. Firstly, it will protect your belt during transport against improper handling and other environmental influences (humidity, temperatures).
Also, if your company is following the very recommendable policy of keeping emergency stock belts (or parts as repair pieces) a proper and protective packing is a must, since this could mean storage over longer time periods.
Examples of an at least “questionable” (left) and proper (right) protective belt packing
Examples of an at least “questionable” (left) and proper (right) protective belt packing

Installation support
The belt producer is the expert for the belt, so they should be able and willing to give you installation support. This doesn’t need to be always personal support on site, since often by far too costly compared to the belt price - but could be done in many other different ways:

- written installation instruction manuals
- series of commented step by step photos of example installations
- recommendation for local service companies who could help with the installation (sometimes this can be the producer’s local agent for the country)
- producer’s availability through modern internet communication media during installation

From the belt producer’s reaction you can very quickly recognize whether there is a general willingness to help you and to not let you be on your own.

Belt Sample
For checking and getting a feeling for several of the above technical points it might be helpful to ask your potential supplier -if he is a new one- for sending you a belt sample so that you can get a better idea about his customer service and that you can “feel the product in your hands”.


The above are hints and clues, I hope, to find and work with a good belt supplier. But the whole process is not a “one-way-street”. Some request should also be directed to the belt user:

  • open mindedness
  • preciseness
  • honesty
  • timeliness

If your belt already looks like this, it is “maybe quite late”.

It is in the interest of the tunnel belt user to start the communication with a (new) supplying partner towards new aspects, ideas and maybe new belt type suggestions open minded. The more precise information you can give, the better it is of course. Be willing to answer questions openly and above and beyond, not “hiding behind the bush” with existing problems and difficulties. And as always, start the discussion in time in order to avoid unnecessary time pressure on both sides.


In my professional life I have worked ~10 years each with a steel producer and with a steel trader, before spending nearly 30 years as an export & product manager with a German belt producer. It is from this experience enriched via personal contacts with clients in roughly 70 countries, that these thoughts and suggestions have arisen.

Belt supplier and belt user should be partners in this game of ‘Give and Take’!
All pictures, clips and snippets shown in this article are examples taken from STEINHAUS GmbH, Germany where my team and I have tried to follow all of the recommendations discussed in this article and have had the privilege of cooperating with >160 tunnel belt clients in >60 countries around the globe. These numbers may substantiate the points that require attention and suggestions in this article.

The world map of Steinhaus GmbH Germany clients

The world map of clients of our company

All readers’ contacts with further questions and comments on this article are welcome!

Peter Otten
Senior Belt Consultant / Germany

A huge thank you goes to PHDs T.Miyashita / L.Otten in Seattle WA for lecturing this article and correcting language insufficiencies.

Leading image: Belt with typical entry zone of a tunnel oven

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