Over the last few years the need for line boring service with a good quality line boring machine has become more obvious at JW Portable Welding & Repairs. Our mobile and portable welders while welding on heavy machinery or equipment have been asked many times if we have line boring capabilities as well as automatic bore welding capabilities. Although, our welding efforts were focused on correcting the damaged equipment alignment, certain alignments were simply impossible to accomplish due to damaged bores.
We have also participated in manual welding of damaged bores in farming equipment ranging from 1″-7/8 to about 4 inches. These relatively low cost partial repairs of damaged bores using SMAW for small bores and GMAW for larger bores have quickly reviled major flaws of manual bore welding without possibility of automatic line boring. Unfortunately, our client had to spent between 10 to 25 hours grinding manually newly welded bore. And, sometimes after so many hours still minor grinding imperfections clearly were visible.
We have researched line boring machines for number of months. The costs of many line boring machines was simply prohibiting for a small company as ours. However, the technology offered was amazing. Generally, we have noticed that these excellent line boring machines manufacturers offer models in capability ranges from 1″-1/4 to about 8″ and then from 8″ to about 20″. Therefore if you would like to bore from 1″-1/4 to about 20″, you would have to buy 2 models.
Then of course you would have to buy a bore welding attachment or as some are calling bore welding machine. And, at the end you would have to also buy plenty of other attachments. The total value of purchases would be about 2 fairly new pick up trucks in more luxury trim level. What kind of small company can afford it?
Our model of line boring machine is capable to bore from 1″-3/8 to 16″-1/2 therefore it almost covers capabilities of 2 models offered by major manufacturers of line boring equipment. The machine centralizes fairly easy and it has digital display and automatic feed.
The bore welding capabilities match our line boring capabilities and range from 1″-3/8 to 16″-1/2. However, we were forced to experiment with bore welding much more extensively. This experimentation has led us into making attachments that make our bore welding smoother and more consistent.
The uniform and consistent welding pattern produced by our automatic line bore welder is paramount for line boring. This is a major difference between manual bore welding and automatic line bore welding. This difference as apparent for small bores as it is for large bores.
Although, we are known for skilled welders, the small bore manual welding was always challenging for them due to traditional SMAW limitations related to beginning of the beat and related to temperature control. Especially temperature control near edges of the bore have caused allays some degree of difficulty. Certainly, we have tried GMAW for these small bores but the gun size prohibited this technique.
You can clearly see the superiority of machine welding of damaged bores in comparison to manual welding of damaged bores.
We have also tried manual welding of larger bores up to 4″ using GMAW. GMAW has allowed us to control the temperature much better than SMAW but it has not allow us to produce the uniform and consistent surface weld in comparison to surface made by automatic line bore welder. Consequently, our clients had to spent hours grinding bumps before going into more uniform weld surface.
The bores play major roles in operation of your equipment. They house bearings, bushings, shafts and pins therefore they provide support for all mechanical parts that rotate. Bores not only sustain vibrations and overloads but also creeping frictions and high temperatures.
After a few years of heavy use bores start to elongate and they become egg shaped. The elongation usually happens at place exposed to extensive loads of stress. Bearings placed to such egg shaped bores do not seat properly and have the tendency to fall off. Shafts at low rotations have characteristic beating noise and at higher speed these shafts excessively vibrate. Such shaft vibration not only damages shaft itself but also surrounding components. Pins placed in egg shaped bores have tendency to bend causing multiple misalignments.
The damaged bores must be repaired for your equipment to work properly. This means that egg shaped bores and double egg shape bores must become perfectly circular.
As simple as line boring is things can get complicated very quickly. The complications usually arise from bore size, severity of the damage, insufficient thickness of the bore’s wall, and severe overload of the bore.
Majority of damaged, “egg shaped”, bores can be fixed with sleeves. The process begins with attaching a line boring machine to the damaged bores. Then the machine makes perfectly circular bores in size much bigger than size of original bore. Then the machine operator measures the newly made bores and produces sleeves that reduce the size of new bores to the size for your pin.
These sleeves after insertion to the new bores are stabilized by welding or by set screws. Both methods of sleeve stabilization bring good results, however, set screws allow for effortless removal of the new sleeve. Removal of a sleeve can be very useful if the machine goes through overhaul periodically and the mechanic replaces damaged sleeves.
Sleeves provide attractive way to fix damage bores as long as bores are relatively small, the sleeve is long enough and the damaged bore has wall thick enough for the sleeve. Once the bores become larger and the ratio of sleeve length to the ID bore becomes smaller than the difficulties starts mounting.
Please notice that if you choose sleeves as a way to fix damaged bores the bore welding is not necessary.
Many bores have significant step out and these bores are more difficult to fix. If we would try to line bore the damaged bores with thin walls and increase their size to make them circular than the bore wall would have become too thin for proper sleeve stabilization. In such cases, we can employ automatic bore welder in damaged places to increase the wall thickness in these places.
The automatic bore welding machine can weld damaged spots located in bores overhead, to the right, to the left and at the bottom of the bore. Once the walls of the damaged bore are in proper thicknesses than the operator can line boring and sleeves to finish it up.
The shallow larger bores make sleeves impractical since stabilization of sleeves in such bores is rather difficult. These shallow bores are characterized by low ration of bore depth to ID of the bore. Although, these bores have sufficient wall thickness, they accommodate only large size and short sleeves. These sleeves are very similar to large size rings and therefore they do not provide sufficient support.
The fixing of damaged shallow bores begins with line boring in order to create circular bore for bore welding. Then the operator proceeds to bore welding which reduces the size of the bore under the size of the pin or shaft. Finally, the operator uses once again bore welding to make the bore exactly to proper size.
High speed bearings usually demand use of bore welding equipment. We do not recommend sleeves in bores of in high speed bearing applications.
We offer portable line boring service out of our portable unit equipped with generator and compressor. We also like to connect the machine to 240V in your shop for more convenience, if possible of course. Once we unload the machine to floor of your shop, we begin to centralize it to the damaged bores.
We always provide estimate prior line boring service.