Hyundai took another big step in its entry into the North American truck trailer market July 23 by announcing development of a refrigerated trailer. The new reefer is designed to complement the dry freight van trailer that Hyundai has produced in its HyMex plant in Tijuana, Mexico, since 1994.
Ted Chung, president and CEO of Hyundai Precision America in San Diego, California, says that Hyundai has earned its credentials as a refrigerated van builder by producing refrigerated containers for the international marine container market for the past 15 years.
Hyundai, with plants in Korea and China as well as Mexico, had a 60% share of the worldwide reefer container market, Chung says. Now, however, with low-cost competition from the many container plants in China, Hyundai's share of the market is down to 40%. He says Hyundai has built about half of the refrigerated containers in the worldwide fleet.
Besides these ISO reefer containers, Hyundai has been building domestic containers in the last year. The HyMex maquiladora plant was set up in 1991 to build ISO steel containers, but that production was phased out during the glut of dry freight containers on the world market three years ago.
The prototype that Hyundai introduced in July is a standard over-the-road refrigerated trailer. It is one of four that will be used in fleet testing service with potential customers. Hyundai engineers started design work two years ago. An earlier prototype was tested at the Bosch test track in Michigan. That 600,000-mile durability test was the equivalent of 10 years of service, according to Ernie Choi, senior vice-president, engineering at Hyundai Precision America.
The Hyundai refrigerated trailer has some uncommon design elements. One is a corrugated roof sheet that has small transverse ribs. These ribs help control the thermal expansion of the roof sheet and help prevent possible delamination of the aluminum sheet from the polyurethane foam insulation. This solution was developed for Hyundai refrigerated containers, and now is a standard feature of Hyundai reefer boxes. Foam bonding is important, says Garry Shidler, QC director. Aluminum sheets are cleaned chemically and a bonding agent is applied before foaming.
Another unusual design is the shape of the aluminum side post. It has a cross section in the shape of a J. The J-post has proven very reliable in Hyundai's refrigerated containers, says Daniel Abal, senior engineering manager. A composite spacer snaps onto the J-section post, with no fasteners needed. Side posts are spaced on 12" centers from the nose through the support gear, and on 24" centers to the rear of the trailer. The composite spacers are added about every 48".
Another unusual design element is a thermal breaker between the rear frame and the inside of the trailer. This composite material is just forward of the rear frame-on refrigerated containers as well as the new refrigerated trailers.
An uncommon feature is variable density foam that can be increased above the ideal two pounds per cubic foot density to increase strength in high stress areas. The sidewall foam behind the scuffband, for example, can be of a higher density to protect this high-impact area. The foam density at the edges of each insulated panel can be increased to three pounds per cubic foot or higher to increase panel strength where the corner joint will be foamed in the assembled van.
Varying the density is easier because of the panel foaming method used. The floor, roof, and two sidewall panels are all foamed in a trailer-length press that controls the expanding urethane foam. The HyMex foam room has two presses and each is a double-decker so that two panels are foamed at one time in each press.
The dimensions of the sidewall spacers or roof or floor spacers determine how far the press platens can close on the panel. These spacers also divide the panel into compartments or cavities for foaming. The computer-controlled foam machine calculates the amount of foam to be injected in each cavity.
Like all production equipment and fixtures in the HyMex plant, the foaming presses were made by Hyundai. Aluminum panels are loaded into the press in a horizontal position. For foam injection, the press platens tilt to an angle. This slope assures a complete fill by gravity, and yet the foam does not have to rise as far vertically. Also, a vacuum is drawn on the press to improve cellular structure of the foam. The cells or "bubbles" tend to be more rounded rather than elongated when foam expansion is assisted by a partial vacuum.
Floors are foamed before the crossmembers are attached, so the floor panel is only slightly more cumbersome to handle in the foam press than are sidewalls and the roof. First the duct-type floor extrusions are seam welded automatically, and then the composite stringers and composite subpan are added before foaming.
Cycle time in the foam room is 20 minutes, so the four panels for one trailer could be foamed in the two double-deck presses, all in one 20-minute period.
The roof sheet is bonded to the roof bows before foaming. When the foamed roof panel is assembled on the van, the roof sheet is riveted to the upper side rail. However, the roof bows are not connected directly to the upper side rail, but float above the side rail lip. Inside, a radius cove is riveted to the ceiling panel during van assembly, and more foam is injected into the roof-sidewall joint to fill that cavity.
The front corner joint is made by riveting to an extruded aluminum corner post. The rivets and corner post are then covered by a smooth composite insert that is curved to a 6" radius.
The standard Hyundai reefer van has 2" thick insulation all around except in the front wall, where it is 4" thick. Panel thickness depends on the size of the composite spacers that are in the sidewall, roof, and floor. Varying the insulation thickness requires purchasing spacers that produce the desired insulation thickness.
Standard lining is a composite one-piece liner, but one of the options is a one-piece stainless steel lining. The sidewall and ceiling liner sheets for this option are .020" stainless steel TIG-welded automatically into one-piece liners before assembly.
Besides the increased durability and cleanability of the stainless steel surface, a primary advantage is that the metal surface prevents moisture or vapor permeation into the foam that is possible with composite linings. The stainless steel option is popular in marine containers, but it does carry a cost and weight penalty, says David Gould, vice-president trailer sales and marketing.
Weight of the standard refrigerated van with 2" insulation in the sides, floor, and roof is 12,700 lb for a 48-ft trailer and 13,200 lb for a 53-ft reefer. The heat loss for the typical trailer with 2" insulation is 130 Btu/hr/ degrees F for a 48-ft trailer or 140 Btu/hr/ degrees F for a 53-ft trailer. Options allow a foam thickness of 2 1/2", 3" and 4" in the sides and roof, and 2 1/2" and 3" in the floor.
Before the startup of the refrigerated trailer line, the HyMex plant was building refrigerated containers at the rate of some 300 to 500 per month. Chung says that production in Korea is three times as large, building 1000 to 1500 refrigerated containers per month. Hyundai has a plant in China building 300 to 500 reefers a month. Hyundai also has two dry freight container plants in China and one each in India and Thailand.
Even so, containers are a small part of Hyundai's output. Shipbuilding, automobiles, industrial plant construction, electronics, petrochemicals and metals are important segments of the huge international conglomerate, Korea's largest corporation. The trailer and container operations in San Diego and Tijuana represent only 0.3% of Hyundai's volume. The total Hyundai volume in 1997 was $90 billion, but this probably will shrink to $80 billion in 1998 because of the Asian financial crisis.
Chung says annual capacity of the HyMex plant is about 8400 trailers, 15,000 container chassis, 8400 domestic containers, and 6000 refrigerated containers or refrigerated trailers.
When the HyMex plant was set up originally, Mexico was a depressed market and the maquiladora plant brought new employment opportunities. Even though Tijuana is a hot labor market now and HyMex must complete with high-tech plants for workers, HyMex still has a labor cost advantage. Chung says the labor cost in the Baja California area just south of San Diego is less than half the cost of labor in trailer plants in the southern and southeastern US. However, the Tijuana plant has cost disadvantages, too, such as higher incoming freight and trailer shipping costs, and dealing with training and supervision in three languages.
Hyundai's home plant in Korea also enjoyed a labor cost advantage 15 years ago, but now the labor advantage has shifted to China and India. So many Chinese container plants are competing for business that the price for a 20-ft steel container in China has sunk below $1600.
Since the HyMex plant opened in 1991, it has built over 33,000 TEU (twenty-foot equivalent units) of steel containers (now discontinues); 76,827 container chassis; 17,687 dry freight trailers; 15,159 domestic containers; and 10,748 refrigerated containers. These figures were quoted as of June 1998.
Current production gives Hyundai about a 2% market share of the North American trailer market, Chung says. "We want to increase this market share to 10%," he says.