Krone-Wabash Gives Norfrig New Beginning

The Krone-Wabash A/S refrigerated trailer plant in Hvam, Denmark, is undergoing rapid changes in order to double its production capacity, extend its marketing area, and develop new products.

The Hvam plant is already the leading manufacturer of insulated bodies in Scandinavia. Started some 30 years ago, it operated as Norfrig A/S until April 15, 2000, when the production facilities were purchased by Fahrzeugwerk Bernard Krone GmbH of Werlte, Germany, in a joint venture with Wabash National Corp of Lafayette, Indiana. Krone is the largest manufacturer of tarp and curtainside trailers in Germany, and Wabash is the largest trailer manufacturer in the United States.

With a market share of 42% in Denmark, 59% in Norway, and 40% in Sweden, the Hvam plant already had a leading position in Scandinavia. Now the Krone sales organization will market the refrigerated trailers and bodies in all the other European countries except France, Spain, and Portugal, where Krone has a joint distribution agreement with Chereau of France.

"This is a new start for us," says Per-Ake Sjolander, managing director. "It makes possible investment in new machinery and new products. We already have the market for increased sales, so we need to double our rate of production and shorten our delivery time."

Six Reefers a Day Historically, the plant had produced from 900 to 1,000 refrigerated bodies a year. By the start of the new year, it had been increased to 30 a week or 1,350 a year (Denmark, like Germany, has to allow for downtime to provide six weeks of vacation periods).

"By the end of the year, we'll be producing at the rate of 50 a week," predicts Sjolander. It won't be easy to reach that mark, because the company has been known for the flexibility to build very specialized refrigerated bodies that take more time to produce. Besides individual customer requests, the various sovereign nations in Europe have very different requirements.

Sweden, for example, requires that its foam-insulated refrigerated bodies be 100% CFC-free. "We were the first manufacturer to provide insulated bodies rated for FRC (deep-freeze) operation to be completely free of chlorofluorocarbons," says Sjolander. "We've been doing it since 1995."

Sweden also allows truck and trailer combinations to operate at a GCW of 60 metric tonnes (132,300 lb). Most other European countries are at 40 or 44 tonnes (88,000 lb or 97,000 lb). A popular combination in Sweden is a tractor, 13.6-meter (44.6-ft) semitrailer, and a full trailer, also 13.6 m (44.6 ft) long.

About 60% of production had been in semitrailers. The other 40% was in truck bodies operating singly or pulling a drawbar trailer. Many truck bodies and trailers have a full-opening side consisting of folding doors with multiple leaves. This requires a rigid box and rigid chassis frame if the doors are to close without binding and fit tightly to prevent air leakage. Some truck bodies and trailers are equipped with meat rails. While the demand for meat rails has dropped, it is now stabilized at a lower level.

Component Outsourcing To meet the increased demand without adding to the plant size (now at 15,000 m superscript 2 (160,000 sq ft), Krone-Wabash will do more outsourcing of components such as steel parts. The stainless steel rear frames and side door frames, for example, are supplied by a fabricating shop in the area. Chassis frames have been supplied for several years by various producers in Europe, but have since April 15, 2000, been delivered by the Fahrzeugwerk Bernard Krone trailer plant in Werlte, Germany, about 300 miles to the south.

To manage the changeover to new production equipment and processes in Denmark, Dr Bernard Krone has appointed a new CEO, Dr Jurgen Fohrenbach, to manage the Werlte trailer operation in Germany, and Dr Krone has moved his offices to Krone-Wabash in Denmark. He hopes to establish new supplier partners in the Hvam region to fabricate parts and components. The Krone-Wabash plant will be even more an assembly plant, in keeping with the modern trend.

FRP Sandwich Panels The key technology of the Hvam plant is insulated sandwich panel design and construction, and the adhesive joining of those panels to assemble insulated bodies. Fiberglass-reinforced plastic (FRP) skins are basic to the sandwich construction, although the company may research the market for metal sandwich construction such as developed by Wabash National Corp.

"Assembly without rivets on the outside is absolutely key to our refrigerated trailer design," says Sjolander. "It is very difficult to sell visible rivets in Europe."

Krone-Wabash manufactures its own fiberglass-reinforced plastic panels using polyester resins. Seamless exterior skins can be impregnated with any color, but 90% are white. The interior skins often have recesses and metal inclusions for later addition of material-handling track and tiedowns, and provision for second-decking beams.

The foam core of the sandwich is applied by different processes, including both foam-in-place within a heated press or hand lay-up of block foam with a polyester adhesive and curing in a vacuum press. Trailer floors, for example, usually are foamed in place, while sidewalls usually are assembled with block foam.

All of the foam is 100% free of chlorofluorocarbons (CFCs). After six years' experience using 100% CFC-free foam, Sjolander says there is little difference in the aging characteristics from freon-blown polyurethane used in the past. The rule of thumb is still about 5% annual reduction in the K-factor for CFC-free insulated bodies. The ATP regulations for insulated truck bodies and trailers require 0.4 K-factor and a retest of vehicles in the sixth year of use to make sure the reserve capacity of the refrigeration unit can pull down and maintain the body at -20???C (-4???F).

Laying Up the Sandwich Panel manufacture starts with fiberglassing the exterior skin. For a smooth, glossy surface on doors and sidewalls, the gel coat is sprayed directly on a polished stainless steel sheet 5 mm (0.2") thick that is glued to a plywood backing plate. After the gel coat sets up, it is conveyed under an automatic chopper gun that applies random glass fibers and polyester resin. Woven aramid fabric is added by hand in areas of high stress and rolled into the resin.

After oven drying at 55???C (131???F), blocks of PVC foam are added around the edges of the form to provide a vapor barrier for the PU foam blocks in the interior. PVC foam is added also at the panel corners and other high-stress areas. Polyester adhesive is applied between and around each foam block.

For sidewalls, an FRP pultrusion Z-post is added every 300 mm (12") along with glass fiber mat and resin to reinforce the sidewalls and tie the two skins together. Steel reinforcing plates for tiedowns and logistics posts are likewise inserted to be glassed to the interior skin.

Workers on a 13.6-meter (44.6-ft) long sidewall have to work quickly to "beat the clock" that starts ticking when they apply the first polyester resin to the exterior skin. The resin has a 45-minute pot life, so the panel must be in the vacuum press by then.

At the same time, workers on the lay-up table are encumbered by protective clothing including hoods and full face masks, tethered with hoses that provide breathing air. Other workers are not so encumbered, because the plant air tests about five parts per million of styrene. Danish regulations allow 25 ppm. The 5 ppm is quite low considering that a concentration of less than one ppm can't be detected by the human nose. Before air is exhausted from the plant, it passes through an incinerator to burn the resin fumes.

The completed sidewalls, roof, and doors are all laid up separately and moved into a curing oven at 55???C (131???F) for 12 minutes under pressure. After curing, each panel is shifted to an automatic saw, router, and drill that are directly linked to the computer-aided-design (CAD) network in the office. These laser-guided machines mill the panel edges to a tolerance of one millimeter (.04").

Floors Foamed in Place Floors also represent quite a departure from reefer floors in the States. The subpan is a continuous sheet of FRP, and on this the wood spacers (crossmembers) are placed. These wood spacers are high-grade multiply birch plywood strips from Finland that are 30 mm and 15 mm (1.18" and .59") thick. A 70 mm (2.75") formed steel channel is at the front and rear of the floor. The top of the sandwich is 21 mm (.827") thick Finnish plywood.

After moving the floor assembly into the heated foaming press, liquid polyurethane is injected into each cavity between plywood spacers. The foam is metered to fill each cavity, and this is assured when the expanding foam is seen coming out of an air hole drilled into each cavity on the opposite side of the floor.

After the foam has cured, the floor is trimmed and milled for precise fit-up with the sidewalls and front bulkhead. Instead of extruded aluminum floors with airflow channels, most floors are a one-piece flat aluminum sheet glued with polyurethane adhesive to the 21 mm (.827") plywood subfloor. This one-piece sheet can be checkerplate or a low-noise version formed with a non-slip texture for use with wheeled carts.

This aluminum plate floor has captured almost 100% of the reefer market in Germany and 25% in other countries. The less costly FRP floor with traction grit is still quite popular. Krone-Wabash has tested the aluminum plate floor with forklift axle loads of 7,200 kg (16,000 lb) and is now aiming for an axle load of 10 tonnes (22,000 lb).

Adhesive Technology Hardware such as logistics track, tiedowns, and second-deck track is attached to the sidewalls and floor. Powered rollover tables have been installed to improve the productivity of these pre-assembly operations and allow all work to be done from the floor level without climbing.

In the case of a trailer with full-opening side doors, all 10 doors are laid out in a row and joined by the hinging and locking hardware. When proper fit and operation are obtained on the table, the entire door-set as a unit is lifted into place. Full-opening sidewalls are popular in Sweden, where after delivery of foodstuffs the trailers are loaded with timber products for the backhaul.

Assembly of the bodies employs more adhesive technology. Polyurethane adhesive fills each lapped joint, and screws and bolts hold the box together while the adhesive cures. Inside the body, the aluminum kick-plate that is part of the sidewall is welded to the aluminum plate floor.

After the box is complete, it is lifted onto the trailer frame and bolted in place. The full-length steel chassis frames are specially designed for insulated trailers. They are manufactured in the Krone factory in Werlte, Germany, where they receive the same extensive anti-rust treatment as Krone platforms. After shot-blasting, they go through a 10-stage decreasing and phosphatizing process, followed by E-coat of the prime coat. The final finish is a baked powder coat that is highly resistant to impact chipping.

The final manufacturing process is washing the trailer and waxing the polyester sidewalls. Polishing makes the sidewalls easier to clean, an important factor in food delivery equipment. Mechanizing the cleaning and polishing process with the installation of a rotating brush that travels the length of the trailer does the work of seven people working manually.

While the full-frame trailer is more or less standard in Europe, the trend for high-cube reefers is a frameless design with only a subframe for the triaxle running gear. Krone-Wabash has completed its prototype of a short-chassis refrigerated trailer with greater internal height, and it is under test now.

Another prototype would move Krone-Wabash into the market for semi-insulated or dry freight vans. It has 25 mm (1") thick sidewalls and a 60 mm (2.36") thick roof. The standard dimensions for a Krone-Wabash insulated trailer are 60 mm (2.36") thick sidewalls with 15 mm (0.59") channels in the sidewalls for recessing the second-deck and logistics track.

Another prototype exhibited at the IAA 2000 commercial vehicle show in Frankfurt is a 34-pallet trailer that has fully legal external dimensions. However, the insulation in the front corners is reduced to provide a 13.6 meter (44.6-ft) inner length sufficient for 34 pallets. This thinner insulation is compensated for by increasing sidewall insulation to maintain the FRC deep-freeze rating.

Future technology will focus on cost reduction and weight reduction, says Sjolander, as well as providing the same type of composite construction with greater internal length and height.

Hide comments

Comments

  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Publish