We often get many questions surrounding the differences between Drawn over Mandrel (DOM) and Cold Drawn Seamless (CDS) Tubing. Both types of cold drawn tubing have close tolerances which results in greater size accuracy. Although, one of the major differences is that DOM is a welded tube while CDS is seamless. Let’s take a deeper look into both of these types of tubing.
Drawn Over Mandrel Mechanical Tubing (DOM) is a cold drawn 1020/1026 electric resistance welded tube with all of the flash removed prior to cold drawing. In comparison to traditional electric welded tubing, DOM tubing is produced to extremely tight OD and ID tolerances. This type of tubing is also known to have the highest weld strength possible. DOM is manufactured in numerous sizes ranging from a 0.188” OD to 12.000” OD with wall thicknesses from 0.028” to 0.625”.
DOM starts as a large coil of steel which is then cut into strips at a certain width depending on the desired tube size. This strip is cold formed and passed through an electric resistance welder which joins the edges of the strip together creating a tubular shape. The tube is then cleaned and annealed and then drawn through one or more dies and over the mandrel. Drawing the tube over the mandrel removes the weld seam from the inside diameter creating a smooth and clean finish.
DOM’s tight tolerances, concentricity, and superior surface quality on the OD/ID surfaces make this type of tubing very cost-effective. The tubing’s close tolerances allow for this mechanical tubing to be used with little to no downstream processing. For more information on what applications DOM can be used for click here.
Cold Drawn Seamless Mechanical Tubing (CDS) is a cold drawn 1018/1026 steel tube. Produced from hot rolled 1026 material. The cold drawing process increases the material's physical properties and offers tighter tolerances compared to hot-rolled products.
CDS is produced from hot solid round billets that are pierced to create a tube. The tubes are subsequently rolled which reduces their diameters and elongates them. The tubes are then slowly cooled before being passed through a die and over a mandrel plug to produce accurate dimensions.
CDS manufacturing process enables this type of tubing to achieve higher physical properties, size accuracy, and enhanced appearance. Although, the tolerances on CDS are not typically as tight as DOM, this type of tubing can be produced with a much thicker wall than its counterpart DOM. The superior strength and hardness of this tubing make for a better-looking component after machining is done to the part. Many industries are fond of the advantages of using CDS so click here to see what application they are using this material for.