1051 FRONTENAC ROAD, NAPERVILLE, IL 60563 • PHONE 630•416•9969 FAX: 630•416•9028
|
1051 FRONTENAC ROAD, NAPERVILLE, IL 60563 • PHONE 630•416•9969 FAX: 630•416•9028 |
|
|
Design Info
VEP specializes in manufacturing a variety of different types of heat sinks. The extrusions supplied by VEP are typically 6063-T5, 6063-T6, and 6101-T6 aluminum alloys. We believe that pressing extrusions is both a art and a science that is best left to the experts. The extrusion mill used by VEP is a world-renowned trusted leader with knowledge and capabilities in pressing all types of extrusion. However, during the design phase there are still many things to consider when dealing with extruded heat sinks. This includes, but is not limited to extrusion considerations such as, cost, tolerances, extrudablitiy, manufacturing considerations and heat sink design. For all new extrusion designs an extrusion die needs to be made. Depending upon the complexity of the profile being extruded, die costs can range from $500 to $5,000. Extrusion dies are designed for specific presses, are proprietary and are not transferable. Extruders typically follow the Aluminum Association Tolerances. This specifies the tolerances that can be held at the various widths, heights and aspect ratios of an extrusion. These tolerances can and do change at various points of the extrusion depending on location relative to the base of the extrusion. Tightening these tolerances can be done at additional cost. Flatness tolerances range from .003 in/in of width to .008 in/in of width. These tolerances do not apply to one inch increments. This can be corrected in two ways. First (most common) during the machining operation at VEP, the mounting area can be machined flat to tolerances as tight as .001” T.I.R. The second method is a corrective roll at the extrusion mill. This can be done, at additional cost, but tolerances can not be held that will typically meet the tolerance required for most semiconductor type devices. VEP’s extruder can currently extrude shapes up to an 18” circle size with a 3:1 ratio. However, technology is always advancing so please do not hesitate to ask about larger sizes. All extrusion mills have minimum pounds per order requirements. Our extrusion mill typically has a minimum order requirement that can vary between 1,000 pounds to 4,000 pounds depending on the circle size of the extrusion. Due to our relationship with our extrusion mill, delivery times for previously tooled extrusion can vary from four to six weeks. New extrusion designs can be delivered to our floor in less than ten weeks. This is substantially better than the industry norm. Extrusion mills run orders in gross poundage rather than in piece part counts. Typically extruders’ terms and conditions of sale allow them to ship ± 10 – 15% of any given order. Again, VEP’s unique relationship with our extrusion mill allows orders placed by VEP to be shipped at a ± 5% of the total order poundage. However, this still allows for finished products to be shipped short from VEP due to material shortages. If an exact material count is required, typically a $500 charge is added to the cost of the material.
MANUFACTURING CONSIDERATIONS - HEAT SINK DESIGN Very few restrictions apply when either drilling or boring holes into heat sinks. Nonetheless, some items in the overall heat sink design must be considered . 1. For small holes, those under .125” in diameter, depth must be considered due to the ability to acquire tooling capable of drilling beyond standard depths. Also drills that intersect fins off center run the risk of being out of round or breaking the tooling. (Fig 1) 2. Tapping a hole through the heat sink, without intersecting any part of a fin, is the easiest and most trouble free tapping process. (Fig 2.)
Tapping that intersects a fin off center run the same risks as drilling into a fin off center. Additionally, this may cause the tap to alter the threads of the hole. (Fig 3.)
This type of tapping also proves difficult to debur and clean. Tapping that does not pass through the material (blind holes) provide several challenges also. Creating a blind hole requires that the hole be drilled deeper than the depth of the threads. As a general rule, the hole must be drilled deeper than the threads by at least twice the diameter of the tap. (Fig 4.)
3. Deburring is a process in which burs are removed from the material. Deburring must be done after the cutting operation and after drilling, drilling/tapping or punching operations. The deburring process after cutting is performed using a wire wheel to remove all burs. This will leave a surface free of burs but with a slightly rough surface around the edges. Deburring after drilling, drilling/tapping or punching is done using powered hand tools. Deburring holes that have an off center intersection with a fin, or when clearance between fins is minimal, must be done by using small hand files. An example of difficult, more costly deburring is shown in Fig 5.
4. Surfacing is a process in which we utilize our CNC machines to remove material from the surface of an extrusion to provide a smooth, flat finish. These finishes are typically 63 micro inches or better and flat to 0.001” T.I.R. We can single pass surface finish for parts under five inches. Items requiring a finish area larger than five inches will require multiple passes of a cutter. For these items, a secondary finishing operation is needed to improve the overall appearance, this generally improves the surface finish. Multiple passes do NOT degrade the overall flatness. The differences between multiple passes have been measured at 0.0002” – 0.0004”. 5. Again, VEP specializes in manufacturing a wide variety of heat sink designs. We believe that aluminum plating is both an art and a science that is best left to the experts. VEP utilizes one of the largest aluminum platers in the Midwest to provide all of our anodize, chromate and nickel plating. Our partnership with them has allowed us to bring short lead times with unsurpassed quality and innovation. Available finishes on aluminum include: a. Anodize colors in blue, black, clear, gold, green, orange, or red. b. Hardcoat Anodize colors in black and clear. c. Chromate in colors gold and clear. d. Electroless nickel.
VEP utilizes a thermally conductive epoxy for all of our bonding applications. This epoxy is by weight 65% aluminum metal and the fully cured material has a higher tensile strength than 1100 Series aluminum (8,900 psi at 25Cº vs. 5,000 psi yield at .2% offset). Other design information
|
|
Send mail to admin@vepinc.com with
questions or comments about this web site.
|
