# Bonus Tolerance (MMC) Position Calculator

> Source: https://netray.co/tools/bonus-tolerance-mmc-position-calculator
> Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems.
> Section: Free Tools

## Short answer

Calculates the bonus tolerance gained as a feature departs from maximum material condition and compares the total allowed position zone to the measured error.

## Category

engineering-plm

## Industry

Discrete Manufacturing

## Audience

- Quality engineer
- CMM programmer
- Design engineer

## Tool

**Kind:** calculator

**Inputs:**

#### Feature type

**Key:** feature_type

**Type:** select

**Default:** 1

**Options:**

##### Hole (internal feature)

**Value:** 1

##### Pin or boss (external feature)

**Value:** 0

#### Material condition modifier

**Key:** modifier

**Type:** select

**Default:** 1

**Options:**

##### MMC (circle M)

**Value:** 1

##### LMC (circle L)

**Value:** 0

#### Size limit at MMC

**Key:** mmc_size

**Type:** number

**Default:** 8

**Min:** 0

**Step:** 0.001

**Unit:** mm

**Help:** Smallest size for a hole, largest size for a pin.

#### Size limit at LMC

**Key:** lmc_size

**Type:** number

**Default:** 8.1

**Min:** 0

**Step:** 0.001

**Unit:** mm

**Help:** Largest size for a hole, smallest size for a pin.

#### Measured actual size

**Key:** actual

**Type:** number

**Default:** 8.06

**Min:** 0

**Step:** 0.001

**Unit:** mm

#### Stated position tolerance (diameter)

**Key:** pos_tol

**Type:** number

**Default:** 0.2

**Min:** 0

**Step:** 0.01

**Unit:** mm

#### Measured X offset from true position

**Key:** x_off

**Type:** number

**Default:** 0.08

**Step:** 0.005

**Unit:** mm

#### Measured Y offset from true position

**Key:** y_off

**Type:** number

**Default:** -0.1

**Step:** 0.005

**Unit:** mm

**Outputs:**

#### Departure from the modifier condition

**Key:** departure

**Expr:** if(eq(modifier, 1), if(eq(feature_type, 1), actual - mmc_size, mmc_size - actual), if(eq(feature_type, 1), lmc_size - actual, actual - lmc_size))

**Format:** decimal

**Description:** How far the actual size is from MMC (or LMC) toward the other limit.

#### Bonus tolerance

**Key:** bonus

**Expr:** max(0, departure)

**Format:** decimal

**Description:** Extra position tolerance granted by size departure.

#### Total allowed position tolerance (diameter)

**Key:** total_tol

**Expr:** pos_tol + bonus

**Format:** decimal

**Primary:** true

#### Measured position error (diameter)

**Key:** pos_err

**Expr:** 2 * sqrt(x_off * x_off + y_off * y_off)

**Format:** decimal

**Description:** Diametral deviation from true position: twice the radial offset.

#### Margin (allowed minus measured)

**Key:** margin

**Expr:** total_tol - pos_err

**Format:** decimal

**Primary:** true

**Description:** Zero or positive means the position passes.

#### Share of allowed zone used

**Key:** used

**Expr:** if(gt(total_tol, 0), pos_err / total_tol * 100, 0)

**Format:** percent

**Chart:**

#### Total allowed position tolerance vs actual size

**Type:** line

**X:** actual

**From:** 8

**To:** 8.1

**Steps:** 20

**Series:**

- total_tol

**Disclaimer:** Assumes the hole or pin is within its size limits and the callout uses MMC or LMC as the position modifier. If the feature is RFS no bonus applies. Verify against your drawing standard (ASME Y14.5 or ISO 2692).

## Content

**Intro:** When a position tolerance carries the MMC modifier, the feature is allowed extra position tolerance as it moves away from maximum material condition. This calculator applies that rule and tells you whether the measured position is inside the resulting zone.

**Sections:**

#### How to use it

**Body:** Pick whether the feature is a hole or a pin and whether the position callout uses MMC or LMC. Enter the size limits, the measured actual size, the stated position tolerance and the measured offsets from true position along X and Y. The calculator returns the bonus tolerance, the total allowed diameter, the measured diametral error and the margin.

#### The formula

**Body:** For a hole at MMC, the bonus equals actual size minus MMC size, where MMC is the smallest hole. For a pin at MMC, the bonus is MMC size minus actual size, where MMC is the largest pin. The total tolerance is the stated tolerance plus the bonus. Measured position error is two times the radial distance from true position, because tolerance is stated as a diameter.

**Bullets:**

- Hole at MMC: bonus = actual - MMC size
- Pin at MMC: bonus = MMC size - actual
- Total = stated tolerance + bonus
- Position error (diameter) = 2 x sqrt(x^2 + y^2)

#### Worked example and mistakes

**Body:** A hole of 8.00 to 8.10 mm with 0.20 position at MMC, measured at 8.06 mm, gains 0.06 bonus for a total 0.26 mm zone. Offsets of 0.08 and -0.10 give a diametral error of about 0.256 mm, so it passes with a small margin. Typical mistakes are forgetting to double the radial offset and applying bonus to RFS callouts.

**Cta:** If position results are keyed into your ERP by hand, we can look at calculating and recording the pass or fail directly from CMM output.

**Faq:**

#### What is bonus tolerance?

**Answer:** It is additional geometric tolerance permitted when a feature of size departs from its maximum (or least) material condition. The looser the fit of the actual size, the more position error the assembly can absorb.

#### Does bonus apply to the datum features?

**Answer:** A separate rule applies. Datum feature of size with a material condition modifier can allow datum shift, which is not covered here. This calculator handles only the toleranced feature.

#### Why is the error doubled?

**Answer:** A position tolerance is a cylindrical zone with a stated diameter. The radial distance from true position must fit within half of that diameter, so the diametral error is twice the radial offset.

#### What if the size is outside the limits?

**Answer:** Then the part fails the size requirement regardless of position. Check the size first, because bonus is only valid within the size tolerance.

## Search terms

bonus tolerance calculator, mmc bonus tolerance, gd&t bonus tolerance, position tolerance at mmc calculator, maximum material condition calculator, bonus tolerance formula, lmc bonus tolerance

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