How smooth is smooth enough? You used to be able to tell by dragging your fingernail across the surface of a cylinder head or engine block. And besides, it didn’t really matter because the composite head gasket would fill any gaps that your equipment or technique left behind.
But with MLS gaskets the requirements have changed. To seal properly, a head gasket requires a surface finish that is within a recommended range. This range varies depending on the type of gasket. Too rough (or in some cases too smooth) and the gasket may not seal properly and leak or fail.
According to surfacing experts, the recommended surface finish for a traditional composite-style soft-face head gasket in an engine with cast iron heads and block is 60-120 microinches Ra (roughness average). The recommended finish for the same head gasket with an aluminum head on a cast iron block is typically 20-50 microinches Ra.
For engines with MLS gaskets, the OEM surface finish recommendations are even smoother, perhaps 20-30 or even 7-15 Ra.
Accurately measuring the surface finish can be done using a profilometer, an electronic instrument that drags a diamond-tipped stylus across the surface to calculate its profile characteristics. The profilometer then shows various values for the surface including roughness average (Ra), average peak height (Rpk), average valley depth (Rvk) and even waviness.
These critical surface finishes require high quality resurfacing equipment to achieve low Ra numbers. Extremely smooth finishes require high quality resurfacing equipment to achieve really low Ra numbers. It doesn’t matter if you use carbide, CBN or PCD tool bits to resurface a head as long as you use the correct feed rate and speed and the equipment is rigid enough to hold the cutter steady so the tool bit doesn’t lift or chatter when it makes in interrupted cut.
For example, a converted grinder may be able to mill heads and blocks. But the spindles and table drives in many of these older machines cannot hold close enough tolerances to achieve a really smooth, flat finish. One equipment manufacturer said grinding and milling machines that are more than five years old are probably incapable of producing consistent results and should be replaced.
Most of the surfacing equipment that’s being sold to shops today has been redesigned for high speed milling with CBN and PCD. The machines have been beefed up with more powerful motors, heavier castings, electrically driven ball screw tables, and tighter assembly tolerances. Some can hold machining tolerances to .0001?!
The information about the head and block surfacing machines included in this report was provided by each individual manufacturer. These profiles are intended to help you determine which machine might best suit your needs but should not be your only source of research. Additional information about each machine can be found on our Web site at www.enginebuildermag.com. In addition, contact information is provided to enable you to contact the suppliers who will gladly answer any of your questions.
Doing the job right may be more challenging than ever, but doing the job wrong may cost you even more.
The DCM HB-3820 is servo-controlled with precision ball screws on both the X- and Z-axis, with downfeed resolution to .0001? (0.002 mm) on the Z-axis. The HB-3820 has the same size capacity as the HB-3810 but has a programmable drive that can be used for multiple cuts and automatic cycling. This surfacer is popular with racers because of its highly accurate controls and ability to achieve Ra finishes in the low teens. The price is in the mid- $40,000 range, depending on options.
DCM Tech, Inc.
The NEW Rottler SFA Surfacing Machines are the answer to improved productivity and profits for automotive and diesel machine shops. Two models designed for the needs of the performance racing team, heavy-duty diesel rebuilder, large production engine remanufacturer, and one-man workshop are available.
S7A/S8A machines have computerized automatic cycles to reduce operator involvement and maximize productivity. when the work piece and the machine are set up, the operator presses the “cycle start” button and walks away. The machine completes the surfacing job and returns to the home position, ready for the next job.
Peterson RP 1010
Maximum milling length: 38.5?
(at maximum milling width)
Maximum milling width: 14?
Maximum length table travel: 45.5?
Automatic table feed per min: 0-34?
Minimum height over table: 6?
Maximum height over table: 22?
Speed of spindle rotation (RPM): Variable
Main spindle motor: 5 (HP)
Workspace required: (L x W): 115? x 36?
Weight (approx.): 2,480 lbs.
Cutting material needed: 1/2? Round CBN, PCD, or carbide
Price (approx.): $18,690
The SM101 CBN Milling Machine Surface Grinder provides a smooth, controlled finish thanks to its electrically driven traversing table with a variable speed table traverse and infinite speed control in each direction.
24? between table and cutter plate accomodate a 440 Chrysler block easily.
Precision ball lead screw increases sensitivity, accuracy and repeatability.
High precision spindle bearings and heavy duty precision construction allow low Ra surface finishes with ease.
Ready to use with standard tooling of universal head and block fixturing, including cylinder head mounting plate, universal rollover fixture and parallel supports.
RMC 10 VB
Maximum milling length: 38?
(at maximum milling width)
Maximum milling width: 14?
Table work surface: 40 x 12?
Maximum length table travel: 42.4?
Automatic table feed per min: 0-190?
Minimum height over table: 0?
Maximum height over table: 21?
Speed of spindle rotation (RPM): 0-1700 (variable)
Main spindle motor: 5.5 (HP)
Workspace required: (L x W): 131? x 46?
Cutting material needed: CBN and PCD
Price (approx.): $29,900
Auto-cycle, full enclosure standard
The T&S Block-Mate (TS-3000) is a high speed surfacing machine that keeps evolving and includes many features that make it one of the easiest and fastest machines on the market. The machine has a universal cradle that works on almost anything and is very fast to setup thanks to the way-mounted dial setup indicator. The Block-Mate can convert from heads to blocks in less than a minute, and can angle-mill a pair of V8 heads in less than 30 minutes. It is uses a unique sliding indicator to align the work piece. It is a single-pass machine that comes with a single CBN insert for milling cast iron or aluminum (PCD can also be used for milling aluminum). The Block-Mate can handle heads and blocks up to 37? long and 14? wide, and is rigid enough to take cuts as deep as .030? at feedrates of up to 60? per minute and can cut in either direction.
Maximum milling length: 47.25?
Maximum milling width: 15.75?
Maximum length table travel: 54?
Automatic table feed per min: 0-130?
Minimum height over table: 0?
Maximum height over table: 29.5?
Speed of spindle rotation (RPM): 0-1400 (infinitely variable)
Main spindle motor: 7.5 (HP)
Workspace required: (L x W): 172? x 54?
Cutting material needed: CBN and PCD (grinding optional)
Price (approx.): $37,900
Auto-cycle, full enclosure, digital readout for stock removal standard.
The DCM HB-3810 resurfacing machine is designed with state-of-the-art controls that simplify and automate the resurfacing process. Features include a powerful 7.5 horsepower motor with class 9 zero clearance bearings to stabilize the milling head (no variations in head height as the motor speed changes), a heavy spindle and dovetail column for added rigidity, a 14? cutter head that holds two CBN inserts, a precision ball screw drive on the X-axis for improved feed control, productivity and reliability. The machine has an automatic feed option available, and can also be configured for grinding. The HB-3810 can handle heads or blocks up to 38? long and 14? wide, and cylinder blocks as large as a Ford 460 (which can be rolled over to resurface both decks). The price for the HB-3810 is low to mid $20,000 range, depending on how the machine is equipped.
DCM Tech, Inc.
Variable speed spindle with digital readout
Variable speed table feed
Ball screw drives on table & column
Flexibility to use either CBN or PCD inserts
Joystick for fast milling head up and down
Standard downfeed indicator
Two modes of operation
Manual allows for continuous back and forth travel for repeated cutting.
Automatic provides optimum removal rates with an auto return feature that prevents back cutting of the cutter plate by lifting off the work piece and returning to the start position.
The SM130M milling machine offers a 51? table traverse to accommodate 3406 Cat and DDC 60 Series heads.
Crank wheel traverse quickly positions head.
Rigid cast iron base and table incorporate flat and v-way design for maximum accuracy and life.
800 and 1600 rpm spindle speeds allow operators to achieve any Ra surface finish and factory desired micro-inch finish with ease.
Cast iron “box” type columns with dovetail ways extend durability and precision.
Winona Van Norman
T&S surfacers are the only machines with an indicator sliding on the ways to set up the work-piece. The Block-Mate comes standard with fixturing to surface blocks and heads. The rapid setup fixture for heads is standard on all models as well. Change over time from heads to blocks is less than one minute. No optional equipment is necessary for any heads, blocks, or intake manifolds. The Block Mate takes up less floor space than other surfacers with a footprint of only 66? x 36?. The price is just under $20,000 with an optional heads only model for $16,500 and an XL (diesel) model for $26,500. A CNC controller for automated machining is an optional feature on all machines.
Rottler S7AD/S8AD machines have CNC capabilities with auto downfeed and optional deck probing with Reinshaw probing system. The AD machines allow operater to set total amount of material to remove and amount per pass, then press the start button and walk away.
Belt driven precision ball screw and infinitely variable speeds and feeds allow surface finished as low as 6 Ra for today’s MLS (Multi Layer Steel) head gaskets.
Dry cutterhead system eliminates coolant disposal and makes cleanup easy. Cutterhead shroud directs dust and chips into chip tray.
Heads can be surfaced in less than 2 minutes, and a pair of V8 heads in less than 8 minutes.
Capable of surfacing Cat 3406 and 3412 heads and diesel blocks such as Detroit V71 and Mercedes 0M440.