11 minute read
Before and afer you buf
from Modern Tire Dealer - October 2013
by EndeavorBusinessMedia-VehicleRepairGroup
Before and after you buff...
By Bob Bissler
Successful truck tire retreaders know that preparing a casing for retreading is an exact science. The visual inspection of a used truck tire is not enough to make sure all the f aws and nail holes have been detected.
Non-destructive testing (NDT) also is required. With computer-controlled NDT machinery, a retreader can produce a f nal product that of en provides more miles than a new tire.
And at less expense. According to the 2013 Modern Tire Dealer Facts Issue, the average price of a new truck tire is $425; the average price of a retreaded truck tire, including the casing, is $230.
“Shearography falls within the NDT category,” says David Stevens, managing director of the Tire Retread & Repair Information Bureau (TRIB). “Some people say, ‘T at’s an NDT machine,’ and some say, ‘T at’s a shearography machine,’ but basically you’re talking about looking inside the tire without destroying it.”
In many retreading operations, shearography is the NDT method of choice, but it’s not the only one. Here are some of the companies that supply NDT equipment, which helps raise your professional standards and makes you a more viable supplier.
The Intact Tire Test System from Steinbichler Vision Systems Inc. horizontally loads truck tires into its vacuum chamber and measures the tires in eight sectors to detect f aws. The company says it can detect 95% of faults.
Steinbichler Vision Systems Inc.
“Shearography is a very sensitive, laser-based inspection technology similar to holography,” says Rainer Huber, NDT product manager at Steinbichler Vision Systems, manufacturers of the Intact Tire Test System.
A separation inside a tire creates a space, and over time air migrates into it. To detect the air bubbles and other f aws, the casing (without the rim) is put into the Intact’s vacuum chamber for under-pressure loading. One measurement is taken at standard ambient pressure, and then the pressure is reduced by 5%. T is is a minor change, says Huber, but it increases the diameter of any air bubbles in tread separations. “T e increasing air bubbles deform the tire’s surface by microns,” says Huber (a micron is one-millionth of a meter). “T at surface deformation can be measured using shearography.”
Michelin Retread Technologies Inc.
According to Mary Ann Kotlarich, commercial public relations director at Michelin North America Inc., Michelin supplies complete retread processes to its franchisees, including shearography, through its Michelin Retread Technologies (MRT) subsidiary. Called the Casing Integrity Analyzer (CIA) system, this proprietary equipment, imaging and analysis system for casing inspection is only available to MRT franchisees.
MRT has shearography equipment in 100% of its plants and requires its use on all casings af er initial inspection. One of them is Valley Tire Co. Inc., which has one MRT facility in Charleroi, Pa.
Stankiewicz has been an MRT retreader since 2007. He says every operator has to be certif ed on each piece of equipment.
Marangoni Tread North America Inc.
According to Giampaolo Brioschi, product marketing manager for Marangoni Tread North America, a division of Marangoni SpA, the Marangoni IT 3000 SFER is the company’s most technical and sophisticated piece of tire inspection equipment of ered.
Brioschi says the IT 3000 SFER ’s principle of testing is based on a comparison between a f rst interference image of the tire surface and a second interference image of the deformed
The ITT 3000 SFERA from Marangoni SpA provides “beadto-bead” inspection without turning the tire. In addition, the non-destructive inspection shearography machine offers an automatic loading and unloading system.
state at decreased pressure. T e dif erence between these two conditions is processed and then displayed on a video screen.
T e SFER , developed by Marangoni SpA, can be used both for the f rst and f nal inspection of the tire, he says. “T at’s the only way to be sure about the quality of the retreaded tire casing.”
Goodyear Tire & Rubber Co.
“T e Goodyear Tire & Rubber Co. does not mandate the use of shearography,” says Todd Labbe, general manager, commercial retread, Goodyear Commercial Tire Systems. “We do of er shearography equipment for our Goodyear Authorized Retreader Network, but only a few of our retreaders use it on a regular basis as part of their process.”
Labbe says Goodyear has conducted evaluations for detecting separations via shearography and dif erometric images, both of which have demonstrated the ability to detect some separations in casings.
Labbe says that shearography is only a small part of the tire inspection process, and it is valid only for indicating possible separations in the tire. It will not work in an area that has been punctured, as this disrupts the vacuum that needs to be part of the system for indicating a separation.
At Goodyear’s Wingfoot Commercial Tire Systems retread facilities, electronic discharge devices f nd nail-hole casing penetrations that can be dif cult to detect visually. Wingfoot retreaders also use a multi-level pressure system to detect weak or broken cords in the upper sidewalls of casings that have not been detectable via other inspection methods, such as X-ray.
“Inspection will continue to be an important part of the retread process, and is a step in the process that technicians should never skip.”
Hawkinson Companies
T e Hawkinson NDT by Hawkinson Companies, a division of Branick Industries Inc., uses electrical impulses to detect
casing f aws. It is a high-voltage tire inspector that the company says is standard equipment for many retreaders. T e Hawkinson NDT’s electrical impulses detect nails, nail holes, cuts, tears and bad repairs that are not visible to the naked eye.
“T e big dif erence between the Hawkinson NDT and a shearograph is that the NDT works on a high-voltage sysThe tem,” says Calvin Sperr, general Hawkinson manager at Hawkinson. “It f nds NDT is a high-voltage system that performs a 17-secany type of penetration in the ond test. When it f nds a tire whether it be a nail hole or f aw in the tire, it will arc to some type of puncture to the that spot and the operator tire that would cause problems can mark where it is and
send it off for repair. The
af er retreading. A shearography unit also inspects for sidemachine runs under a vacuum wall defects three-quarters system which looks for separaup the side of the tire. tions in the belt package in the tire.”
T e Hawkinson NDT inspects casings prior to buf ng and can test up to 200 tires per day. Since it is independent from buf ng, it does not slow down the retreading process, notes the company. T e unit also can be used to inspect tires af er
buf ng, af er repairs and at f nal inspection af er retreading.
Sperr says retreaders also use the NDT before shearography because if there is a nail hole, it must be repaired f rst.
The Hawkinson NDT machine has been used by tire remanufacturers such as Michelin Retread Technologies, Bridgestone Bandag LLC and Wingfoot Commercial Tire Systems for nearly 30 years.
The Bandag 7450 Insight uses shearography to scan sidewalls and locate ply failures. Flaws will show up on the unit’s monitor when it displays an image of the scan.
Bridgestone Bandag Tire Solutions LLC
T e Bandag 7450 Insight Casing Analyzer uses shearography to scan crown/beads/sidewalls and locate ply failures. T e company says that when Bandag dealers upgraded their casing inspection capabilities with this new technology, f eets started to notice improvements in retread reliability. (T e unit is only available to Bandag franchisees.)
Flaws will show up on the unit’s monitor. T e operator can select any section of the tire for further investigation. A truck tire can be completely scanned in minutes, and no lif ing is required of the operator. T e result is a dynamic image that shows the surface of the crown, bead, sidewall or inner liner. Any measured change will be displayed and may indicate a defect in the casing.
Continental Commercial Vehicle Tire
T e Continental Commercial Vehicle Tire business unit of Continental AG recommends that its retreaders invest in pressure testing equipment in addition to conventional shearography. T e company suggests using shearography as the f nal method of performing casing inspection to verify radial sidewall strength.
“Also known as a ‘boom box’ for the loud sound made if a tire ruptures at the highest inf ation stage, the Mat uezzi G100 machine recommended by Continental’s ContiLifeCycle retread
Retreading trend Marangoni pioneered shearography
Marangoni Tread North America Inc., a division of Marangoni SpA, says it was a pioneer in producing shearography inspection equipment in 1998. According to Giampaolo Brioschi, product marketing manager, the market for shearographs was strong when the new technology was introduced, and in recent years it has become more stable.
“Our research and development department is continuously and fully committed to improve and to f nd out innovative solutions in such an important sector as tire casing inspection,” says Brioschi.
According to Rainer Huber, NDT product manager at Steinbichler Vision Systems Inc., two major retreading trends today are making the use of shearography systems increasingly necessary.
“First, casings are becoming harder to source due to weaknesses in the new tire market,” says Huber. “Due to the growth of new tire manufacturers getting involved in retreading, they strive to retain ‘their’ casings within their own systems.
“Second, there has been a new focus in recent years on quality among medium-sized retreaders, and that is becoming ever more important. Both customers and the competitive business environment demand this. To retreaders who continue to believe that they can’t afford investments of around $130,000, an investment in shearography has always been crowned with economic success for those who have taken the step.”
The Mattuezzi G100 machine, recommended by Continental for its ContiLifeCycle retread process, utilizes three stages of inspections, which are measured at 25 psi, 65 psi and 115 psi, to reveal f aws in casing sidewalls.
process engineers utilizes three stages of visual inspections,” says John Barnes, Continental’s manager of ContiLifeCycle activities in the Americas.
Different inflation pressures are used during the three inspection stages, which are measured at 25 psi, 65 psi and 115 psi. T e pressure levels are adjustable.
At the 25 to 65 psi levels measured by the G100, distinct ripples or waves can sometimes be detected in the casing’s sidewall, which indicates a weakened or broken steel body ply section.
“A casing sidewall section of this type could rupture under operating conditions, something that no retreader — or f eet — wants to experience. Inspecting a casing under pressure as the f nal step can help identify tread and casing separations, missed repairs, other tire deformities and of -center treads. Some of these deformities can be missed, even with conventional shearography.”
Barnes says the result of this pressure testing is the peace of mind of ered to both f eets and installers that the casing has been proven sound at operating inf ation and the retreader has taken multiple steps against zipper ruptures.
“A casing rupture at these inf ation pressures can be deadly, so we encourage our retreaders to make the additional investment in the G100 or similar pressure testing equipment.”
Barnes says that because of the increased focus on safety and non-destructive testing in recent years, most reputable retreaders are aware of the need for complete and thorough inspections. Advocacy for safety by industry groups has made shearography, inf ation cages and advanced training in retread practices fairly commonplace. However, Barnes said they may not realize that the extra step of pressure testing is a quick and af ordable process.
“Continental’s ContiLifeCycle retread process engineers estimate that carrying out pressure testing takes only an additional two minutes per tire, and costs only an additional 74 cents per retread. It’s well worth the investment. Continental helps our ContiTread licensed retreaders to obtain this equipment at an af ordable cost, which pays of in terms of safety to their employees and their customers.” ■
