June 7, 2017
MEMORANDUM
TO:		EPA-HQ-OAR-2017-0358
FROM:	Korbin Smith SPPD, MMG
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SUBJECT:	Industry Characterization for Friction Materials Manufacturing Facilities NESHAP

	
      The purpose of this memorandum is to provide industry characterization for the Friction Materials Manufacturing Facilities source category. The information summarized includes material gathered for the EPA's proposed residual risk and technology review, as well as past documents used in the initial National Emissions Standards for Hazardous Air Pollutants (NESHAP). There are two major sources subject to this rulemaking (Knowlton Technologies and Railroad Friction Products Corporation). Data was provided through a questionnaire sent to both of the major sources subject to the NESHAP. Section 1 describes the type and purpose of products manufactured within the source category. Section 2 provides a summary of the manufacturing process used to create the products of this source category.
       
1. Friction Materials Manufacturing Facilities Industry

1.1 Product and Manufacturing Overview 
	
      Friction material manufacturing is a broad source category that covers a wide assortment of products. The 2002 NESHAP describes a friction materials manufacturing facility as a facility that manufactures friction materials using a solvent-based process. Friction materials are used in the manufacture of products used to accelerate or decelerate objects. Products that use friction materials include, but are not limited to, disc brake pucks, disc brake pads, brake linings, brake shoes, brake segments, blocks, brake discs, clutch facings, and clutches.
      The two major sources subject to this rulemaking produce very different products. Railroad Friction Products Corporation produces train car brakes. Knowlton Technologies produces friction paper products utilized in several different processes including appliance motors, automotive transmissions, motorcycle transmissions, industrial equipment, power take-off (PTO) clutches, launch clutches, torque converters, transfer cases, limited slip differentials, machine brakes, and sealed wet brakes. For additional information on the two facilities see memorandums (Site Visit Report-Knowlton Technologies, LLC and Site Visit Report-Railroad Friction Products Corporation) available in the docket for this rulemaking (docket ID: EPA-HQ-OAR-2017-0358). 
   
1.2 Characterization of the Friction Materials Manufacturing Facilities Industry

      There are only two major source facilities subject to the friction materials manufacturing facilities NESHAP. Both facilities were visited by EPA staff during development of the rulemaking and the companies provided data used in this rulemaking via a questionnaire attached to the site visit letter. There were four facilities subject to this regulation when the NESHAP was promulgated
      The NESHAP established two subcategories based on the size of the solvent mixer. A small solvent mixer is defined as a mixer with a design capacity less than or equal to 2,000 lbs. A large solvent mixer is defined as having a design capacity of greater than 2,000 pounds. Both remaining facilities have large solvent mixers. 


2.0 Friction Materials Manufacturing Facilities Manufacturing Process

2.1 Overview of Process

Due to the large variability in products made within the Friction Materials Manufacturing Facilities source category, the process from one operation to the next can be very different. One commonalty between both major sources is the use of a solvent mixer. As mentioned in section 1.1, a friction materials manufacturing facility is a facility that manufactures friction materials using a solvent-based process. 
The solvent mixer is used to blend raw ingredients to form the friction product. The raw materials processed in the solvent mixers include reinforcement materials, property modifiers, fibers, solvents, and other additives. The equipment used in the raw material preparation area accomplishes the mixing of these raw materials in the proportions necessary to produce friction materials with the desired specifications.[2]
Materials are mixed in discreet batches. When solvents are used in preparing the friction materials, the solvents are typically added as a process aid for further process operations. The solvent mixers are typically batch mixers operated at slightly elevated temperatures. Typically, the reinforcement material, property modifiers, fibers, and any other additives are loaded into the mixer, and then the solvent is added. After mixing, the material undergoes further processing before being heated (cured) into the final product. 


2.2 Emission Characteristics

      At the time of the NESHAP, the EPA believed that HAP emissions from the manufacturing of friction materials was driven almost entirely by the use of HAP-containing solvents used in the mixing operation.[1] This understanding hasn't changed as data has shown almost all HAP emitted from the source category is released from the solvent used in the mixing operation. Most emissions from the HAP containing solvent occur at the mixing operation, however, residual emissions can be found at various downstream processes as it is further heated and processed.

