Sheet Metal – Metric Gage Substitutions for Imperial Gage Sheets

In Asia, sheet metal stock is more commonly available in metric gage rather than imperial (used widely in the USA).  The following table lists the recommended substitutions for imperial gage sheets, when the available stock is metric.

Imperial Gauge Imperial in mm Metric Sheet mm
10 3.25 3.0
12 2.64 2.5
14 2.03 2.0
16 1.63 1.5
18 1.22 1.2
20 0.91 0.9
22 0.71 0.7
24 0.56 0.6
26 0.46 0.5
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Sheet Metal Thickness Tolerances

What range of tolerances can we expect from standard steel sheet stock used in sheet metal fabrication? The main cause of variability in sheet stock thickness: during the rolling process that produces the sheet stock, a certain amount of “bowing” occurs in the rollers. This results in the sheet being slightly thinner at the edges than at the center of the sheet.

Gage Nominal Max Min 36” sheet 48” sheet
10 0.1345 0.1405 0.1285 0.006 0.009
11 0.1196 0.1256 0.1136 0.005 0.007
12 0.1046 0.1106 0.0986 0.004 0.006
14 0.0747 0.0797 0.0697 0.004 0.0055
16 0.0598 0.0648 0.0548 0.0035 0.005
18 0.0478 0.0518 0.0438 0.003 0.004
20 0.0359 0.0389 0.0329 0.002 0.003
22 0.0299 0.0329 0.0269 0.002 0.003
24 0.0239 0.0269 0.0209 0.0015 0.002
26 0.0179 0.0199 0.0159 0.0015 0.002
28 0.0149 0.0169 0.0129 0.0015 0.002

Depending on the requirements of the design and intended functionality, this variation can have significant impact on the quality, consistency, and acceptability of the part being fabricated.

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Carbon Steel Cross Index (Commercial Designations)

The following table is a list of carbon steels commonly used in industry, along with their alternate names and designations in their worldwide commercial use.

Material Code and Material Name Worldwide Commercial/Alternate Designations
1103, Carbon Steel T-1 T-1; T-1 Type A; T-1 Type B; USS T-1, T-1 Type A, T-1 Type B
1201, High Strength Steel 4130 4130; AISI 4130; SAE 4130; 4130H; UNS G41300, H41300
1203, High Strength Steel 4140 4140; AISI 4140; SAE 4140; 4140H; UNS G41400, J14046
1204, High Strength Steel 4330V 4330V; 4330; 4330 Mod; 4330V Mod; 4330V (Mod+Si); UNS J23260, K23080
1205, High Strength Steel 4335V Mod 4335V Mod; 4335 Mod; UNS K33517
1206, High Strength Steel 4340 4340; AISI 4340; SAE 4340; E 4340; 4340 H; UNS G43400
1207, High Strength Steel 52100 52100; E 52100; Teton (Allegheny-Ludlum)
1208, High Strength Steel 8630 8630; AISI 8630; SAE 8630; 8630H; UNS J13042, J13050, G86300
1209, High Strength Steel E9310 E 9310; SAE 9310; AISI E 9310 H; AMS 6260 E; UNS G93106
1210, High Strength Steel 17-22A(S) 17-22A(S); 17-22A(V); Uniloy 14 MV (Universal Cyclops designation for 17-22A(S))
1213, High Strength Steel D6A D6A; D6AC; UNS K24728, K24729
1214, High Strength Steel Hy-Tuf Hy-Tuf; UNS K32550
1215, High Strength Steel Nitralloy 135 Mod Nitralloy 135 Mod, Type G Mod; AMS 6470 Nitriding Steel; SAE 7140; UNS K24065
1216, High Strength Steel Hy-130/140 HY 130, 5Ni-Cr-Mo-V Steel; UNS K51255
1217, High Strength Steel 300M 300M; Tricent; 4340 Mod; UNS K44220, K44540
1218, High Strength Steel H-11 Mod H-11 Mod; AISI Type H-11; SAE Type H-11; UNS T20811; Al Tech Potomac A
1218, High Strength Steel H-11 Mod Carpenter No. 882; Chromo-V; Gutrel H-11; Hot Form No. 2
1220, High Strength Steel 18Ni (250) Maraging 18Ni 250 Grade Maraging Steel; UNS K92890, K92940; Almar 18 250; Marvac 250
1220, High Strength Steel 18Ni (250) Maraging Nimark 250; Udimar B-250; Vascomax 250
1221, High Strength Steel 9Ni-4Co 9Ni-4Co; HP-9-4-20; HP-9-4-30; UNS K91283
1223, High Strength Steel 18Ni (200) Maraging 18 Ni Maraging Steel; 18Ni-Co-Mo; 18Ni (200) Maraging; 18-8-3; Vascomax 200 CVM
1223, High Strength Steel 18Ni (200) Maraging RSM 200; Almar 18
1224, High Strength Steel AF1410 Unimach 1410; AF 1410
1225, High Strength Steel 18Ni (300) Maraging 18Ni Maraging Steel; 18Ni-Co-Mo; 18-9-5; Vascomax 300 CVM; RSM 300; Almar 18
1225, High Strength Steel 18Ni (300) Maraging Marvac 300; 18Ni (300) Maraging Steel; 300 Grade Maraging Steel
1225, High Strength Steel 18Ni (300) Maraging 18 percent Nickel Precipiation-Hardening Steel; Grade C-MAR-18-300
1226, High Strength Steel 9Ni Steel 9 Ni Steel
1227, High Strength Steel M50/M50NiL Steels M50: AISI M50; Carpenter VIM-VAR M-50 Bearing Steel
1227, High Strength Steel M50/M50NiL Steels M50: Latrobe CM-50 High Speed Steel; Latrobe Lescalloy M50 VIM-VAR Bearing Steel
1227, High Strength Steel M50/M50NiL Steels M50: Vasco M-50 High Speed Tool Steel; UNS T11350 (K88165)
1227, High Strength Steel M50/M50NiL Steels M50NiL: Latrobe CBS-50NiL VIM-VAR Carburizing Bearing and Gear Steel
1228, High Strength Steel Maraging T-250 Maraging T-250; Maraging MS 250; Maraging Free-Co
1229, High Strength Steel AerMet 100 AerMet 100; UNS K92580
1230, High Strength Steel H-13 H-13; H13; AISI H-13; Premium AISI H-13; ASTM H-13; SAE H-13; Material No. 1.2344
1230, High Strength Steel H-13 40CrMoV5; Cast Grade CH-13; GX40CrMoV5-1; X40CrMoV5; ESR H-13
1230, High Strength Steel H-13 8407 SUPREME, 8407 2M (Assab); Nu-Die V, Nu-Die XL, Nu-Die ESR (Crucible)
1230, High Strength Steel H-13 Orvar Superior, Orvar 2M, W302 SUPERIOR, ISOBLOC (Bohler-Uddeholm)
1230, High Strength Steel H-13 No. 883, Extendo-Die, Pyrotough 78 (Carpenter)
1230, High Strength Steel H-13 DH2F (International Mold Steel); MTEK T90813 (MetalTek)
1230, High Strength Steel H-13 THYROTHERM 2344 EFS, 2344 EFS SUPRA (ThyssenKrupp)
1230, High Strength Steel H-13 THYROTHERM 2367 SUPRA ESR, 2344 ESR MAGNUM (ThyssenKrupp)
1230, High Strength Steel H-13 VDC H-13, TLS H-13 PQ, LSS H-13, LSS H-13 PQ (Latrobe)
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Machining of Very Large Shafts (Fabricated, Forged, or Cast)

SANDMARK has the capability to fabricate/forge/cast shafts of large diameter and lengths, and machine them to precise dimensional requirements.

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Metals and Materials Testing Capabilities

At SANDMARK, as part of our full contract manufacturing services, we offer the full range of materials testing, including mechanical testing and chemical analysis. All tests are conducted by NABL accredited labs, with globally accepted procedures. If you require specific and custom tests according to your specifications, we can readily accommodate them, please call with your requirements.

Mechanical Testing

  • Tensile test
  • Bend test
  • Fatigue test
  • Compression test
  • Compression test for springs
  • Hardness test (HRC/HRA/HRB)
  • Impact test at range of temperatures from room- to –50C

Microstructure Analysis of Metals

  • Micro hardness Vickers
  • Macro structure with photographs
  • Austenitic grain size
  • Microstructure of steel, cast iron, aluminum, and copper alloys
  • Microstructure of Ni, Ti, Mg, Zn, and their alloys
  • Inclusion rating
  • Case depth/decarburisation layer thickness: microscopic method
  • Case depth/core hardness by micro-hardness: survey method

Spectrometer for Material Composition AnalysisSpectrometer for Material Composition Analysis

Metallurgical MicroscopeMetallurgical Microscope

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Checklist for Info. Required in your Castings RFQ

In order for us to provide you with complete and comprehensive quotes, we appreciate you provide us with the following information in your Castings RFQ packet:

  1. Drawings by Operation (if available): most of our customers provide us with separate drawings for castings and machining for each component. This is very beneficial for all parties and eliminates confusion. For complex parts larger than 3 inches, we recommend you provide a casting drawing based on ISO GD&T, a separate drawing for machining, (and if necessary in some cases) a third drawing for finishing.
  2. Volume and/or Weight: in order for us to quote, we need to know the volume of the part, or weight.
  3. Material and grade: Please specify clearly the material specifications, and also the grade and class of material that you require for the casting.
  4. Solid Models: It is critical for us to receive solid models of your parts, along with your drawings. The most common format is 3D IGS. We also accept Solidworks, Pro/E, Solidedge, CATIA, UG, and Inventor. If you have other formats, please contact us to discuss.
  5. Tooling Drawings: As part of your design process, if you develop/design tooling drawings for patterns, jigs, fixtures, and/or dies, please forward this to us. This will reduce development time considerably.
  6. Usage in Assembly: For some castings, it may be useful for us to know and understand where the castings will be used in assembly. With this information, we can better comprehend critical dimensions, and also provide feedback to you for improving manufacturability, lowering costs, and enhancing performance.
  7. Quality/Testing Requirement (see below)

Quality Plans

Along with your drawings, we also appreciate you provide your quality plan for the components. This quality plan can list all your requirements and specifications for producing acceptable parts, including

  • Material testing requirements
  • Certifications as needed
  • Tooling requirements, if available
  • Finish requirements, including coatings as needed (specify RA value and depth as required)
  • Destructive test plans
  • Non-destructive test plans, including sample sizes and quantities
  • Inspection requirements, inspection plan, and required reports

With the above information available to us, we can provide you the full quote, and guarantee that the parts that we supply to you will meet your requirements, consistently. With incomplete information, we are forced to make assumptions that may lead to confusion down the road.

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Gear Quality Number (Q-Number)

SANDMARK can manufacture and supply high quality gears, up to Gear Quality Number AGMA 14 (or DIN 3, or ISO 3).  The Gear Quality Number is also known as the Q-Number or the Gear Quality Grade.  The Q-Number for a gear is a measure of the geometric accuracy level of teeth on the gear.

While the standard used in the USA is set by AGMA (American Gear Manufacturer’s Association) ; other regions of the world use different standards for gear teeth quality. The following table provides a general cross-reference between different standards (JGMA – Japanese Gear Manufacturers Association , ISO – International Organization for Standardization , and DIN – Deutsche Industrial Normen). However, note that there is no direct and full conversion between the standards. The cross-reference table below notes the ‘likeness’ of the Q-Numbers in each standard.

AGMA (USA) ISO (INTERNATIONAL) DIN (GERMANY) JIS (JAPAN)
13
4
4
0
12
5
5
1
11
6
6
2
10
7
7
3
9
8
8
4
8
9
9
5

Higher the Q-Number in AGMA, the higher the quality of the gear.  Inversely, a lower Q-Number in ISO/DIN indicates higher quality.

A typical Gear Quality Measurement Report from SANDMARK is shown below.  The gear being measured here has been manufactured to a Q-Number of ISO/DIN 6-7, or AGMA 10-11.

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Gas Nitriding Chromoly and Nitralloy Steels – Minimizing Distortion

What is Gas Nitriding?

Gas nitriding is a type of case-hardening process whereby nitrogen is introduced into the surface of a solid ferrous alloy (steel) by holding the metal at a suitable temperature in contact with a nitrogenous gas, usually ammonia. The nitriding temperature for steels is between 495 and 565°C (925 and 1050°F).

During nitriding, nitrogen atoms are absorbed into the surface to form hard nitrides. The maximum limit on case depth is about 0.040 inch (1.0 mm) maximum (in certain materials such as Nitralloy 135); typically 0.5 mm or less is achieved in AISI 4000 series steels.

Advantages of Gas Nitriding

Main advantages of gas nitriding are: very low distortion compared to carburizing or conventional hardening. Reason: no quenching is involved, and the nitriding temperatures are lower than other hardening processes.

Nitriding of Gears

SANDMARK uses nitriding extensively for many different gears that we manufacture for our customers. Nitriding is especially suitable for precision gears because gears have symmetric geometry (which is critical for nitriding), and precision and high-speed gears cannot tolerate even minor distortion and deformation, and require high levels of wear and pitting resistance.

Materials

Typical steels that are condusive to nitriding are chromoly steels and Nitralloys. Nitralloys are especially suited for nitriding.

Process

Typical sequence of processes employed by SANDMARK for nitriding resulting in low distortion and high repeatability: (1) core harden – quench and temper (2) rough machine (3) stress relieve (4) finish machine/grind (5) Nitride (6) optional: remove white layer by lapping

Pre Processing

Material must be hardened and tempered before being nitrided. The tempering temperature must be high enough to guarantee structural stability at the nitriding temperature.

In certain alloys, the hardness that can be achieved during nitriding is dependent on the core hardness of the part coming in. Hence, in order to obtain maximum case hardness, these steels should be provided with maximum core hardness by tempering them at the minimum allowable tempering temperature.

Single Stage Nitriding

In the single-stage process, a temperature in the range of about 495 to 525°C (925 to 975°F) is used, and the dissociation rate ranges from 15 to 30%. Single stage nitriding results in the creation of an iron nitride ‘skin’, about 0.001″ to 0.002″ thick. The white layer is not as hard as the case underneath it, and is very brittle. Frequently, this layer is asked to be removed. Lapping is an effective way to remove the white layer. The white layer can also be minimzed by employing dual-stage nitriding.

Dual Stage Nitriding

Dual stage nitriding, also known as Floe process, is simply two single stage processes back to back (the times are different however). Dual stage process is used primarily to reduce the thickness of the white layer (dual stage nitriding minizes the white layer to 0.0006″ or less). It can also increase the case depth especially if a higher temperature is used in the second stage.

Minimizing Distortion, Deformation

  • Residual stresses from prior operations such as welding, hardening, machining, etc. can get relieved during nitriding, causing distortion of the geometry. Careful pre-processing which includes tempering will minimize this issue.
  • Poor Process Control: Stresses are introduced during nitriding due to inadequate support in the furnace, or too rapid or nonuniform heating or cooling. Precise process control minimizes this issue.
  • Uneven case depth is caused by inadequate surface preparation, which will cause distortion. This can be minimized by vapor degreasing, or by careful surface preparation.
  • Geometry Factors: When the nitrided case develops, it expands. After the part cools to room temperature, the case region will be in compressive stress and the core area will be in tensile stress. If the part and the case are not symmetrical, the stresses are not balanced and distortion occurs. Because of this, nitriding is appropriate only for symmetrical parts such as shafts and gears. This distortion is dependent on the material being used and the geometry of the part.
  • Grinding/Finishing Before Nitriding: All grinding (and finish machining) operations should be carried out to the final dimensions pior to nitriding. In nitrided parts, there is a balance between compressive stresses in the case and tensile stresses in the core (see ‘Geometry Factors’ above). If this balance is upset by grinding off a part of the case, it is possible to see dimensional instability over time. If the white layer needs to be removed, lapping should be used. Parts not ground after nitriding have excellent dimensional stability.

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Should Gray Iron Castings be Stress Relieved?

Some suppliers do not stress relieve gray iron castings, and some do.  As a rule, SANDMARK stress relieves all our gray iron castings.  Common reasons for presence of stresses in castings are: different cooling rates in different parts of the casting after it comes out of the mold (due to complex geometry with varying thicknesses, thin sections, surface/geometry curvatures, etc.).

Over time (periods of months to a year), castings left alone will relax and stresses will dissipate.  During this relaxation period, the geometry and dimensions of the castings will ‘move’ gradually, and eventually stabilize.  However, it is not practical to cast and ‘season’ (although it used to be the practice decades ago with large castings).  Hence the need for stress relieving.  This is especially important if machining operations are required post-casting, with sub-thousands (of an inch) tolernaces in relational dimensions between features.

It is not inconcievable that a casting with has not been stress relieved can meet all dimensional requirements at the factory, and over time (during transportation, sitting on the shelf), can move out of specifications. Hence, stress relieving is a necessary procedure for all castings that need to maintain dimensional stability through their useful life.

While different options are available (thermal, vibratory, shot-peen, etc.), the most common (and most effective) choice for small to medium sized castings is thermal stress relieving.  The following is a typical stress relieving treatment employed by SANDMARK for our gray iron castings (24 hours full cycle, with about 6-8 hours of soak at approximately 550 C).

Typical Profile for Stress Relieving Gray Iron Castings at SANDMARK

Typical Profile for Stress Relieving Certain Gray Iron Castings at SANDMARK

When to stress relieve:

Typically, it is best to stress relieve after rough machining and just prior to final machining.  Because of logistical and other cost considerations, it may be tempting to stress relieve raw castings and then perform machining operations with no further treatment.  However, machining operations can also introduce varying degrees of stresses into the part.  By stress relieving immediately prior to final machining, both casting stresses and machining stresses can be removed prior to final machining, thereby the best possible outcome can be achieved.  For castings with demanding precision requirements, it may be necessary to stress relieve twice, once after the casting comes out of the mold and again after rough machining.

Reference:

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SPOT – Online Order Tracking System

SPOT – SANDMARK Online, Real-time order tracking system is now available to our customers. This online, web-based tool allows our customers to view, in real-time, the status of all items in the orders that are in process with SANDMARK. The Tracker can be accessed at http://www.sandmarkmfg.com, or from the SANDMARK home page at www.sandmarkglobal.com.

Please contact your SANDMARK Global Account Manager to obtain an username and password for SPOT.

SANDMARK SPOT Logo

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Automotive retainer nut and ring/washer

SANDMARK is now manufacturing and supplying high precision retainer nut and ring/washer for a customer in the automotive market.  Material is EN19 Steel

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Partner Focus: Earle Durham & Associates

Earle Durham & Associates is a Sales Management Consulting firm, with an emphasis on the business-to-business marketplace.  They can assist clients in significantly improving their “Sales Force Effectiveness”, measured by revenue growth, increased profit margins, and faster market penetration.

SANDMARK’s partnership with Earle allows us to round out our offerings to our Industrial Customers with offerings in the sales and marketing service areas.

Please contact us with your interest, or Earle directly at 919-995-5796, or via email.

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Custom Manufactured Brass Fittings

SANDMARK just delivered a production lot of custom brass fittings to a customer in North America.  These brass fittings were manufactured in Asia.  Operations/processes employed to produce these fittings were: casting, machining, thread cutting.

Custom Brass Fittings

Custom Brass Fittings

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