Test Panel Information Sheet ChemInstruments realizes that test panels change over time and these changes can cause questions concerning accuracy and repeatability in test results. Our dedication to detail and customer service enables us to make the most accurate and reliable panels on the market. We pride ourselves on the consistency of product that we have provided to the marketplace since 1987. ChemInstruments panels are manufactured in accordance with PSTC specification, Appendix B, section 2.6. They also meet other standard agency specifications such as ASTM D1000. This excerpt has been taken from the handbook published by the Pressure Sensitive Tape Council: Test Methods for Pressure Sensitive Adhesive Tapes 16 th Edition (2014) 2.6 Panel Specification 2.6.1 A 50 x 125 x 1.2 mm (2 x 5 x 0.048 in.) ± 10% panel of 304 stainless steel, free from burrs or sharp edges, having a bright annealed finish. The surface roughness shall be 0.05 ± 0.025 microns (2 ± 1 micro inches) (Ra). The deviation in flatness in both the machine and the cross direction of the bright annealed surface shall be 0.125 mm (0.005 in.) maximum. The surface shall be free of contaminants such as process oils, and visual defects such as blemishes and scratches. 2.6.2 Panels with other shapes and dimensions may be formed or cut from the same steel and finish when specified by an individual method. The surface, directional flatness, and edges should still meet the requirements of 2.6.1. This paragraph will be cited with the necessary exceptions. 2.6.3 The bright annealed surface of any panels during storage or shipment should be covered with a residue free wrapper. 2.6.4 Panels showing or developing stains, discoloration, or scratches are not acceptable. ChemInstruments purchases stainless steel sheet metal in the 304 bright annealed form. Only one side of the material is finished to the specified surface described above. It is always delivered to our facility with a protective vinyl covering on the finished surface. This covering ensures the integrity of the surface during panel processing. The thickness specified for a panel must be 1.2 mm (0.048 ). This thickness is referenced by sheet metal standards as 18 gauge material. All stainless steel panels that ChemInstruments sells are made from 18 gauge material. 304 Stainless Steel is the most widely used variation of the 18/8 grades. The 18/8 references 18% Chromium/8% Nickel blended with Iron. It is a very versatile metal and has excellent Page 1 of 5
forming and welding characteristics. More importantly, it is a highly corrosion-resistant compound. This makes it particularly good to use in chemical or wet applications. It is made up of the following elements and ratios: Carbon 0.080% max Manganese 2.000% max Phosphorus 0.045% max Sulfur 0.030% max Silicone 0.750% max Chromium 18.00-20.00% Nickel 8.00-10.50% Nitrogen 0.100% max Iron Balance The surface finish specification dictates that the panel material must have a bright annealed finish. This type of finish is created at the steel mill by cold rolling, then annealing the material to the specified thickness. Annealing is the process of heating metal to a high temperature to work the metal, then allowing the metal to cool at its own rate. The annealing process is a procedure of running the metal through a series of rollers to draw down the metal to the required thickness or gauge. The final annealing process is done using highly polished rollers which impart a glossy finish resembling a cloudy mirror. Performing the annealing process in an oxygen-free environment eliminates any chance of oxidation or scaling during the processing of the material. 304 stainless steel having a bright annealed finish is typically referenced as a 2BA finish. This refers to a standard 2B finish performed in an inert furnace environment leaving the material bright or shiny. The 2B finish is created by the high polish finish on the final rollers used to perform the final gauge pass. Through pressure, the high-polish finish transfers to the material, making the surface very smooth. The surface smoothness of a panel is required to be 0.05 +/- 0.025 microns (2 +/- 1.0 micro inches) (Ra). Ra refers to the mathematical average roughness of a surface for a defined longitudinal period. Ra is expressed in micrometers (µm), otherwise known as microns. This measurement is performed using a device known as a profilometer. It is an extremely precise device which pulls a diamond tipped stylus across a small line of a surface to read the peaks and valleys of that surface. Upon moving the stylus across the surface, the internal computer of the profilometer then calculates the Ra value from the data collected. The panel flatness specification requires that a panel must not have a deviation in flatness more than 0.125 mm (0.005 ) in either of the length or width directions. This is performed first by placing a panel onto a large block of precisely finished granite known as a surface plate. The top of the surface plate is highly polished to an extremely smooth and flat finish. The panel is observed resting on the surface plate visually noting any flatness variations. It is then pressed on all corners to note any rocking. Any visually noted rocking would describe a piece largely out of specification. More precise measurements are made using a height gauge to note flatness variations on random points of the panel surface. Page 2 of 5
Processing Before processing the panels, ChemInstruments ensures that the raw material used to make panels meets the above requirements. Below is a detailed description of how ChemInstruments processes all stainless steel panels. It is quite a long process, but we feel that all of these steps are required to create the most accurate and repeatable panels in the industry. 1. ChemInstruments has purchased the same specification of material from the same vendor since beginning business in 1987. We have not changed suppliers for the specific reason of consistency. This supplier is one of the larger metal suppliers in the business. Using the same supplier assures that the material is QC checked to the same standards every time we purchase material. This does not mean that they are the producers of the material; that would be the foundry. The foundry may change from time to time based on the metals market, but the supplier has the buying power to ensure that the material always meets their product standards. 2. The PSTC standard that the product adheres to is only the specification for the type of steel and the finish (304 stainless steel, bright annealed). This is specified by the metals industry. The metals industry specification does not call out a surface roughness parameter as stated in the PSTC handbook. (We have found the product to be very consistent throughout the time that we have been in business.) 3. We purchase the material in lots of 50 sheets, sized 1.22 m x 1.52 m (48 x60 ), 18 gauge, bright annealed 304 stainless steel. This helps ensure that we get a large sampling for consistency. We require that every sheet is prepared with a protective vinyl covering laminated to the "good" side ensuring the protection of the product for accurate and repeatable testing results. 4. We require the supplier to provide certification of every lot for tractability. We keep that document on file. Each lot is numbered sequentially by ChemInstruments staff upon arrival at our facility. We began using this lot numbering system for traceability in the year 2000. Typically, we deplete an entire lot of material every 6-7 months. 5. We perform a surface roughness check on all four corners of every fifth sheet in the entire lot. Each corner is checked in two directions - with and against the "grain" of the metal. We use a profilometer to measure and record the surface roughness (Ra). We keep records of the results along with the vendor certification mentioned above. Each panel cut from that lot is acid etched on the "bad" side with traceability information: ChemInstruments name, phone number, date, web address, and lot number. (Some of this information has changed over the years as technology has advanced.) 6. We have a very detailed process for cutting and handling the panels. This process not only ensures a safe panel for the user to handle, protecting the user from being cut by the sharp edges, but it also ensures that the panel stays free of scratches and other contaminates prior to shipment to the customer. Throughout this process, the vinyl protective covering remains on the good surface to ensure the best quality. This procedure has been used since 1997 with great success. 7. After the panels are fully processed, we store them for shipping in a safe location. When panels are ordered, we carefully wrap them and place in a box for shipment. Each order Page 3 of 5
of panels is sent with a Test Panel Tips sheet. This is a document authored by ChemInstruments and contains valuable information regarding panel care and handling. These tips have resulted from many years of learning about and working with panels. This sheet discusses proper handling and cleaning procedures that will ensure the panels remain in good shape for years to come. Many of these hints go beyond the standard procedures outlined by PSTC and other related groups. Usage Once the panels have been received, the user will find that the panels have a protective vinyl covering laminated to the good side. This covering will need to be removed and the surface under it must be cleaned in a special manner prior to use. The Test Panel Tips sheet supplied with every order details the steps that must be taken to properly clean the panel for initial use. These instructions are also discussed in the PSTC handbook in Appendix C, Addendum. Additionally, Appendix C also details the general cleaning procedure for panels throughout their useful life. The purpose for the more rigorous cleaning procedure outlined in the Addendum is to fully remove all of the manufacturing debris left on the surface of the metal which cannot be removed easily. The processing fluids and adhesive residue from the vinyl covering can be quite difficult to remove using the standard cleaning procedures outlined in Appendix C. The main step that thoroughly eliminates the contaminants from the panel surface is the baking procedure. It is a necessary step to burn off any deep rooted contaminants in the surface roughness which cannot be dissolved using the standard cleaning procedure. Once the initial procedure has been performed, the panels will need to be cleaned to the standard procedure noted in Appendix C before finally being ready for testing. In some cases, the initial cleaning procedure might need to be performed a second time to remove very difficult contaminates from the panel surface. These deep contaminants can sometimes be seen in the surface of the panel as a cloudiness or haze. This haze is part of the manufacturing process and cannot be fully removed by cleaning. Solvents simply cannot get down into the microscopic lines in the panel surface to remove all of the haze. The only process we have found to help remove the haze is the initial cleaning/baking procedure, which is outlined in the Addendum. If this haze is not removed, it can affect the test results for many uses until the panel is cleaned thoroughly. The PSTC panel specification and cleaning procedure does not specify cleaning in regard to the haze. The helpful hints that we have included in the Test Panel Tips sheet come from years of dealing with the inconsistencies of the base material beyond the PSTC specification. This is most noticeable when comparing new panels to old ones, since the old panels may have been cleaned tens or hundreds of times based on their age and/or frequency of use. With this haze, it is typical that new panels may not yield as great a peel force as compared to older panels. This is due to the older panels having more clean surface for the adhesive to bond. Even with the initial cleaning procedure performed, the new panels may still have contaminants that will only come loose with repeated cleaning. Page 4 of 5
Super Panels ChemInstruments has noted the importance of a highly cleaned panel to be the foundation of superior test results. We have performed numerous studies over the years relating to panel cleaning conditions. We have also worked closely with many industry leaders regarding this topic. By combining that data along with the wants of our customers, in 1999 we introduced an improved alternative to the standard panel described above. We call this panel a Super Panel. The Super Panel begins with the same 304 stainless steel material used in a standard panel. We then check it for the correct profilometer readings. At this point the raw sheet material is redirected to be buffed. An entire sheet is sent thru a wide web buffing machine that deep cleans the surface of contaminates. This process uses a non-abrasive cleaning compound combined with a soft buffing roller using light pressure. It is then buffed, washed, and a new protective vinyl covering is laminated to the good side. The buffed material is then redirected back to the same steps as a standard panel. After the panels are cut, deburred, and serialized, the Super Panel process continues. The vinyl protective covering is removed, and then the panel is cleaned with an MEK wiping. Batches of cleaned panels are placed into an oven for one hour at 175⁰C (350⁰F). Once they have been removed and left to cool, they are cleaned again with an MEK wiping using lint free wipers. Panels that have been cleaned and are dry are then stacked with lint free tissues separating them to keep them clean and free of scratches. The Super Panel process cleans a panel more effectively, thus shortening the start time to testing. The recipient of a new lot of Super Panels can quickly clean the panels by following the procedures outlined in Appendix C and start using them immediately thereafter. Numerous studies have shown that Super Panels bring the data into specification sooner than a standard panel since they are super clean. Pricing on Super Panels is slightly higher than standard panels, but the added service yields consistent results much sooner than standard panels. We hope that this information sheet has been informative and helpful in answering some of the questions that arise from buying new panels. It turns out that panels are much more complex than they appear and the cleaning process becomes a very important part of the break-in period of new panels. Please contact ChemInstruments for further information regarding panels at: (513) 860-1598 or info@cheminstruments.com Page 5 of 5