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For pipe fabricators operating at high volumes, wrinkles on bent tubing are far more than a cosmetic flaw-they cause rejected parts, production disruptions, and higher costs per part. Most would assume wrinkle formation is related to die design and material, but actually the method of feeding plays a surprisingly significant role. Erratic feeding, off-center starts and incorrect positioning at the start of the bend induce localized stress concentrations which then buckle the inner radius in the form of wrinkles. With a purpose built auto-loading system, the BR40NCB hydraulic pipe bender eliminates the inconsistencies introduced by manual tube feeding and presents every part identically into the bending cycle. This feature proves to be very valuable for mass production applications where the machine runs tens of thousands of parts a day.
Eliminating Feed Variations at the Source
When manually loading tube into the bending dies, there is simply no way for the operator to perfectly center the material and keep the tube consistent with the stop with steady forward pressure. This slight irregularity forces uneven stress distribution at the start of the bending cycle creating wrinkle formation as compression forces build on the inner wall of the bend. With a precision feed the BR40NCB auto-loader feeds the tubing to within hundredths of a millimeter of the target position, time and time again. With servo-controlled feed force, every single part every single cycle starts with precisely the same material pressure at the exact same location of the bend cycle.
Synchronizing Feed with Bending Motion
It’s critical to have constant control over the relationship between the speed of tube feeding and the angular velocity of the bend. In manual loading, feeding is done in conjunction with bend arm movement by the operator and it requires an immense degree of concentration not to overfeed or hesitate — which again forces localized compression stress into the inner wall of the tubing and causes it to buckle into a wrinkle. The fully automatic feeder is completely synchronized with the bending axis so that feed rate corresponds precisely with rotational velocity, delivering material at exactly the rate it's consumed by the bend cycle. As the tubing continuously flows into the bend cycle and wall thickness remains uniform, the localized stress on the inner wall of the bend is within acceptable elastic limits and no wrinkle is formed even at high production speeds.
Maintaining Consistent Lubrication Coverage
Lubrication on the tube surface drastically decreases frictional forces against the bend and pressure dies, which are a prime cause for wrinkling. Inconsistent lubrication (either too much or too little lubricant) from manual application and storage is far more common than one might expect, resulting in an abundance of rejected parts and significantly increased cleaning costs. The BR40NCB automatically applies a measured dose of lubricant to the surface of the tubing just before contact with the die. As it feeds, the quantity is precise and the location is optimal. Constant lubrication helps the outer surface slide efficiently and allows the inner surface to be compressed rather than being stressed through friction and wall thickness variations.
Reducing Setup Variability Between Batches
In the mass production setting, it is not uncommon for the same machine to be changed over many times in a single day for new jobs with different diameters, wall thicknesses and bend radii. Every setup presents an opportunity for wrinkles to occur. Even a minute misplacement of a pressure die set can ruin an entire batch — often before wrinkles are even visible in the production run. With a fully programmable control, the BR40NCB is capable of storing and recalling exact set-up configurations including the amount of insert, the position of the pressure die and its speed, all of which are fed into the automated loader and integrated into the bending sequence. Once set, a perfect wrinkle-free job can be repeatedly produced for tens of thousands of parts with very little concern about variation.
Here at Baorui, we've spent the last twenty years of our business focused on providing pipe fabrication and bending machines. Through that time, we've identified numerous causes of common industry problems such as wrinkles — from improperly sized dies and incorrect material types to wrong wall thicknesses and improperly set machines. But more often than not it comes down to inconsistency, and no process introduces more inconsistency than manual loading. By utilizing a truly automated and robust auto-loading system, Baorui's BR40NCB delivers consistently perfect parts, batch after batch, making it the premier choice for high volume work in industries like automotive, furniture, and others where perfectly formed parts are a necessity, not a luxury.