"Demand is driving our capacity to its limitations," said Greg Hancock, ThermoFlex vice president and general manager, in a telephone interview.

"We need equipment for more capacity, bigger part size and cost effectiveness," Hancock said from ThermoFlex's Morrison, Tenn., operation.

The firm's expansion includes a three-station, rotary thermoformer supplied by Monark Equipment Technologies in Auburn, Mich. The new machine, when installed in early March, will allow ThermoFlex to increase part size to 6 feet by 10 feet and improve energy efficiency.

ThermoFlex's product line includes trays, dunnage, material-handling components and other returnable packaging for automotive OEMs and their suppliers. The main body of the packaging is made of thermoformed or vacuum formed commodity resins like polyethylene, ABS, and polypropylene.

Much of the packaging contains injection molded or reaction injection molded polyurethane or thermoplastic rubber inserts to help hold delicate parts, such as transmission components, in place during transportation.

To boost insert production, ThermoFlex is adding several injection molding presses with clamping forces of 150-700 tons in Morrison. Many of the presses will be transferred from sister company PolyFlex Products LLC of Farmington Hills, Mich.

Hancock and PolyFlex CEO Mark Kirchmer declined to provide the cost of the ThermoFlex expansion.

"The OEM gives us a part and we design, make and supply packaging for it," Hancock said.

Besides automotive, ThermoFlex is branching into other markets such as trucks, buses and recreational vehicles. It already is diversified in urethane-coated rollers and parts for conveyors, tool-protection holders for metalworking, a range of assembly tools, bumpers, enclosures, grippers, covers, part protectors, wipers and seals.

Hancock said the Morrison operation includes in-line thermoforming of purchased sheet. Eventually it plans to add cut sheet lines to the mix.

ThermoFlex expects to add 10-15 employees, more than doubling its staff, after the expansion.

ThermoFlex and PolyFlex share some common ownership and are management-owned.

PolyFlex was established in 2003 with fewer than 10 employees, recalled Kirchmer. By 2012 it had grown to 49 full-time and 28 part-time positions.

PolyFlex moved from Livonia, Mich., to Farmington Hills in early 2012 to consolidate manufacturing from two plants and to share administration and engineering with ThermoFlex. The consolidation involved a small urethane molder PolyFlex acquired in 2007.

PolyFlex focuses on returnable packaging more so than ThermoFlex. It started in the appliance sector and has grown into automotive. It runs eight injection presses in Farmington Hills, with clamping forces of 200-1,000 tons. It exports globally.

"We see more opportunity to replace paperboard components with plastic," Kirchmer explained in the telephone interview.

Plastic part nests can be returnable or expendable.

PolyFlex molds urethane, plastics and rubbers and also does foamed urethane.