Inspection#

Estimated time to read: 46 minutes

Generally, an inspection is an organized examination or formal quality evaluation exercise.

Inspection activities can involve the measurements, tests, and gauges applied to certain characteristics in regard to an object or activity. The results are usually compared to specified requirements and standards for determining whether the item or activity is in line with these targets, often with a Standard Inspection Procedure in place to ensure consistent checking.

There are three primary types of quality inspections: pre-production, in-line, and final. There are a variety of details that must be inspected and approved during each phase in order to detect and correct quality problems.

This document will guide you through the required configurations for the Inspection functionalities.

Overview#

Inspection is a common practice in the industry to ensure the desired level of quality. It is common in the industry to implement an inspection plan based on sampling, being AQL (Acceptance Quality Limit) a very common method.

An Inspection consists in taking a sample out of every Material being processed and recording the values of Parameters to be controlled. All the processed Materials are inspected and it must be a User to select the units of the sample to be inspected, even though MES can provide some guidance on which sample units should be inspected.

An Inspection can either be performed in the production step itself or there can be separate dedicated inspection steps. Furthermore, an Inspection will have a pass or fail result depending on the number of acceptable defects.

• The Sampling Plan is used to implement counter-based and time based sampling, to send Materials to a Sampling Step, whereas in an Inspection Plan all the Materials being processed are inspected.
• The Sampling Pattern is that the Sampling Pattern is used to set a Sampling Selection that defines which Sub-Materials must be sampled at a particular Step and in which sequence. In-Step Sampling can be used separately or in combination with Lot-based Sampling as provided by a Sampling Plan. On the other hand, the Inspection functionality only provides a hint of which/how many sample units are to be inspected.

The Critical Manufacturing Inspection-related concepts and functionalities will be described in more detail over the next sections.

Setting up Inspection Related Entities#

To enable the Inspection functionalities, it is necessary to set up the Critical Manufacturing MES entities.

• A production Flow that comprises two production Steps: Parts Manufacturing and Parts Assembly. The Step to be controlled by the inspection is the Parts Manufacturing.
• An Inspection Plan that comprises five inspection Steps: Parts Inspection Strength, Parts Inspection Color, Parts Inspection Width, and Parts Inspection Thickness. The goal of the Inspection Plan is to support the inspection of production Materials which are tracked-in in the Parts Manufacturing Step through five inspection steps. The Samples of the Inspection Steps Parts Inspection Color and Parts Inspection Width are returned to the Production Flow to the Parts Assembly Step. The Sample of the Parts Inspection Thickness Inspection Step is not returned to the Production Flow since it is a destructive test.

In order to set up the Inspection related Entities, it's necessary to follow the steps as described in the Table below.

Table: Steps to setup the Inspection related Entities

The next sub-sections will cover the required configuration steps in more detail.

Concepts#

The table below describes the main concepts related to Inspection.

Table: Inspection main concepts

The concepts presented above are linked to the MES object models displayed in the figure below.

1 - Create the necessary Resources#

To perform an inspection it may be required not only to have the right Instruments but also to ensure that those are correctly calibrated. Furthermore, for the Inspection Steps, Resources of Processing Type Process or Line must be configured. If an Instrument is required, it must be attached to the Process Resource and calibrated when performing an inspection on a sample.

To create an Instrument, the properties listed in the table below need to be defined.

Table: Resource properties

Manage Instrument Capabilities#

After the creation of an Instrument, it is possible to characterize it by the following capabilities: Parameters, Measurement Units, Range, Resolution, Precision, and Accuracy, as detailed in the Table below. The Manage Instrument Capabilities wizard can be accessed through the Resource Details page in the Measurement Capabilities section.

Table: Manage Instrument Capabilities properties

At least one of the Resolution, Precision, or Accuracy properties must be defined.

Measurement Capabilities can also be copied from other Instruments, using the 'Copy All Measurement Capabilities' Option, as displayed in the Figure below.

Change Instrument Mode#

To define the Instrument Mode, you must access the Change Instrument Mode wizard available in the Resource View, as displayed in the Figure below. The Instrument Modes available are the ones defined as Measurement Capabilities.

Manage Resource Instruments#

To associate an Instrument to a Resource, you must access the Manage Instruments wizard through the Resource page. You can either select an Instrument through the search box or through a barcode reader, as displayed in the Figure below. You can check which Instruments are attached to a Resource in the Instruments section of the Resource page.

To select an Instrument the following conditions have to be met:

• The Resource must have the Processing Type defined as Process or Line
• The Resource and the Instrument must be in the same Facility
• If the Instrument property Exclusive Usage is set to True, then it can not already be associated with a Resource

Apply One Instrument to All Applicable Parameters#

If an Instrument is used to measure multiple Parameters, you can choose the Apply to All option, as shown in the wizard below.

2 - Create the necessary Data Collections#

The collection of data for a sample during an Inspection is performed through a Data Collection. The properties to be configured are detailed in the Table below.

Table: Data Collection properties

The Parameters' configuration can also be copied from other Data Collections, using the 'Copy Parameters' Option.

Data Collection Parameter Frequencies#

The Data Collection Parameter Inspection Frequency defines how the size of the Samples is calculated for a Material being inspected. Each Frequency will be detailed over the next sub-sections.

Acceptance Quality Limit (AQL)#

Acceptance Quality Limit (AQL) Sampling is a method used to define if a lot/production order meets the customer's requirements through random sampling. This method complies with the ISO 2859-1:1999, ANSI/ASQ z1.4 2018, and the MIL-STD 105E standards.

An AQL Strategy should be agreed upon between the buyer and the supplier and is defined by the following parameters:

• Inspection Level - determines the number of samples to inspect from a production lot
• Inspection Severity - determines the number of acceptable defects. There are three types of Severity: Normal, Tightened, and Reduced
• There are three types of Defects Classification. The proportion of acceptable defects vary in function of the product and its market.
  • Critical Defects (Percentage) – Defects that when accepted could harm users. Such defects are unacceptable
  • Major Defects (Percentage) – Defects that are usually not acceptable by the end-users, as they are likely to result in failure
  • Minor Defects (Percentage) – Defects that are not likely to reduce the usability of the product for its intended purpose but differ from specified standards; some end users will still buy such products

The percentage of Defects depends on the product type and can be determined through the table below.

Table: Percentage of Defects per product type

The first step to obtain the number of samples is through a code letter that can be derived from the table below, having the lot size and the desired Inspection Level.

The code letter determines the sample size. Along with the selected Inspection Severity and Acceptance limit, it provides the maximum number of acceptable defects. Each Inspection Severity has its own table (Inspection Severity Table). Below are the tables for a Normal, Tightened, and Reduced Inspection Severity, for a Single Sampling Plan.

The arrow pointing upwards means that the first sampling plan above the arrow will be used. The arrow pointing downwards means that the first sampling plan below the arrow will be used.

For example, having a production lot with 20 000 units and an Inspection Level II, the code letter is M. Looking at the Sampling and Acceptance Limits table for a Normal Inspection Severity, the number of samples is 315. If the AQL is set at 2.5% for major defects and 4.0% for minor defects, the lot is accepted if no more than 14 units with major defects and no more than 21 units with minor defects are found.

An example is displayed in the Figure below.

Any#

The Any Inspection Frequency intends to inspect any one of the units being produced.

An example is displayed in the Figure below.

Centering#

The Centering Inspection Frequency intends to calibrate the production process by measuring the produced units until those are within the expected values (Data Collection Limit Set Warning Limits). Once a unit is centered, only the last unit needs to be measured.

If a sample reading is out of the defined Data Collection Limit Set Warning Limits, a new sample is created so that a new measurement can be performed on the next unit being produced in order to ensure that the process is calibrated within the spec limits.

An example is displayed in the Figure below.

Counter Based#

The Counter Based Inspection Frequency intends to inspect a certain number of units of a Material depending on a defined Counter Frequency. For example, if a Material Primary Quantity is 20, the Inspection Frequency is equal to 5 and the Sample Source is:

• Sample Number: four Samples must be inspected
• Piece Number: Pieces 5, 10, 15 and 20 must be inspected

An example is displayed in the Figure below.

First#

The First Inspection Frequency intends to inspect only the First unit being produced.

An example is displayed in the Figure below.

First And Last#

The First And Last Inspection Frequency intends to inspect the First and Last units being produced.

An example is displayed in the Figure below.

Fixed#

The Fixed Inspection Frequency intends to inspect a fixed number of units (Sample Size) being produced.

An example is displayed in the Figure below.

Last#

The Last Inspection Frequency intends to inspect only the last unit being produced.

An example is displayed in the Figure below.

Percentage#

The Percentage Inspection Frequency intends to inspect a percentage of the number of units (Percentage Value) being produced.

An example is displayed in the Figure below.

Data Collection Parameter Sample Type#

The Data Collection Parameter Sample Type defines the type of the Parameter, i.e. the type of information that a User will provide about the Parameter.

Attribute#

The User will provide for the Parameter the quantity of sample that has Passed and Failed.

Result#

The User will select if the sample Parameter has Passed or Failed.

Defect Count#

The User will provide for the sample and Parameter the observed number of defects.

Variable#

The User will provide the Parameter value for the sample.

3 - Create the necessary Data Collection Limit Sets#

When collecting data for a Data Collection Parameter in an Inspection, a Data Collection Limit Set Parameter must be provided if:

• The Data Collection Parameter Sample Data Type is set to Variable, which has both the Target, Lower Error Limit, and Upper Error Limit defined
• The Data Collection Parameter Inspection Frequency is set to Centering, which has both the Target, Lower Warning Limit, and Upper Warning Limit defined

4 - Create the necessary Steps#

To consider a Step for inspection, the properties listed in the Tables below must be configured. Please note that an Inspection can be performed not only in a production Step but also in dedicated inspection Steps.

In the Edit Step wizard, you can configure the properties listed in the Table below.

Table: Step properties

The Manage Inspection Information wizard can be accessed through the Step Details view, in the Inspection section.

In the Manage Inspection Information wizard, in the General tab, you can configure the properties listed in the Table below.

Table: Manage Inspection Information - General tab properties

You can define Contexts to apply Inspection Configurations different from the Default Configurations listed in the Table above. Those can be defined in the Manage Inspection Information wizard, in the Context Information tab, as listed in the Table below. For further information please check the Manage Inspection Severity Instances sub-section.

Table: Manage Inspection Information - Context Information tab properties

You can define Rules which will change the Severity in use depending on the results of previous Inspection Orders, for a certain context. In the Manage Inspection Information wizard, in the Switching Rules tab, you can configure the properties listed in the Table below. For further information please check the Switching Rules sub-section.

Table: Manage Inspection Information - Switching Rules tab properties

• Parts Manufacturing
• Parts Assembly
• Parts Inspection Strength
• Parts Inspection Color
• Parts Inspection Width
• Parts Inspection Thickness

However, it is only required to access the Manage Inspection Information wizard for the Parts Manufacturing Step, i.e. set the Enable Inspections property to True and define the remaining required properties.

Manage Inspection Severity Instances#

It is possible to define different Inspection Severity Instances per Context, besides the Step Inspection Default Configuration, if you define a Context in the Context Information tab. The Manage Inspection Severity Instances wizard can be accessed through the Step Details view, in the Inspection section and it is displayed in the Figure below.

The Context information can be manually added in the Inspection Severity Instances or, when a Material is tracked-in, a Severity Instance with the Material Context and Inspection Severity will be added to the Inspection Severity Instances.

Switching Rules#

A Switching Rule will be run when Closing an Inspection Order for a Material if there is a match between the Material Severity Instance Context (defined in the Severity Instances) and a Switching Rule's From Inspection Severity (defined in the Step Switching Rules). If the condition of the Rule is met, the To Inspection Severity configurations will be set for the Material Severity Instance Context.

For example, having the Material Type Context defined and the Switching Rules and Severity Instances defined as displayed in the Figures below. If a Material having the Material Type Production will have its Inspection Order Closed, MES will run the NorMoreInspectionsFailed Rule. If the last Inspection Order for that Context had failed, then the Severity Instance for the Production Material Type Context will have its Severity changed to Reduced, as well as the corresponding configurations.

5 - Create the necessary Flows#

After configuring the production and inspection Steps, the corresponding Flows must be defined.

• A Production Flow having the Steps: Parts Manufacturing and Parts Assembly
• The following inspection Flows:
  • Inspection Flow 1 having the Steps: Parts Inspection Strength, Parts Inspection Color, and Parts Assembly. The Parts Assembly must be the last Step of this Flow since the Material will return to this Step in the Production Flow
    • Inspection Flow 1.1 having the Steps: Parts Inspection Width and Parts Assembly. The Parts Assembly must be the last Step of this Flow since the Material will return to this Step in the Production Flow
    • Inspection Flow 1.2 having the Step: Parts Inspection Thickness

• Material Samples must be created after the Material is processed in the Step
• To merge two Materials those must have the same System State

For the given example, the Parts Inspection Color and Parts Inspection Width Steps can't be merged into the Parts Manufacturing Step.

6 - Create the Inspection Plan#

The Inspection Plan will define the Inspection Steps and the samples' flow throughout the Inspection Steps.

To create an Inspection Plan, the properties listed in the table below need to be defined.

Table: Inspection Plan creation

Table: Inspection Plan Steps example

7 - Define the Inspection Plan Configurations#

An Inspection Plan must have defined which Data Collection and Data Collection Limit Set will be used in each Inspection Step. This can be defined as an Inspection Plan Configuration. An Inspection Plan can have several Configurations defining different Data Collections and Data Collection Limit Sets for the same Inspection Step. To create an Inspection Plan Configuration, the Manage Inspection Plan Configurations wizard can be accessed through the Inspection Plan Details page, under the Configuration section.

To display all the Inspection Steps, the button flagged in the Figure below can be selected.

The Inspection Plan Configuration Steps can also be copied from other Inspection Plan Configuration Steps that belong to an existing version of the same Inspection Plan, by using the Copy Steps option.

8 - Define the Inspection Plan Context#

To define the contexts of the production Step for the Inspection Plan, you must define the Inspection Plan and Configuration in the Inspection Plan Context. This can be defined through the Add Inspection Plan Context Record(s) wizard, which can be accessed in the Step Context view, in the Inspection Plan Context section.

Using Inspection#

After setting up the required configurations mentioned in the previous sections, the Inspection functionalities can be used, as described over the next sections.

The Inspection functionalities are described in the Table below.

Table: Inspection functionalities

1 - Track-In Material#

When performing track-in of a Material in a Step of a process to be controlled via inspection (with an Inspection Plan context defined), an Inspection Order will be created. This means that, in order to ensure a desired level of quality, random samples will be collected from all the Materials tracked-in in this Step.

If the Step's property Require Instruments On Track-In is set to True, instruments that can measure the required Data Collection Parameters must be associated with the Resource. The Instrument Calibration Status must be set as Calibrated. Furthermore, if the Data Collection Parameter defines an Instrument Type, the Resource Instrument Type must match that Instrument Type.

For every Inspection Plan Step, an Inspection Order Step will be created as well. For each Inspection Order Step, the system will resolve a Data Collection and Data Collection Limit Set, if applicable. If the Data Collection Parameter Inspection Frequency Configuration Mode is Automatic, the Data Collection Parameter properties will be inherited from the Step in which the main Material is being tracked-in. If the Data Collection Parameter Inspection Frequency Configuration Mode is Manual, the Data Collection Parameter properties will be inherited from the Data Collection Parameter.

Furthermore, depending on the Inspection Frequency and, as mentioned in the previous paragraph, depending on the Inspection Frequency Configuration Mode, the Sample Sizes will be calculated as described in the Table below.

Table: Sample Size calculation for each Inspection Frequency

2 - Create Samples#

After tracking-in a Material with an associated Inspection Order and if the Inspection Order has the property Includes Separate Inspection Steps set to True, you must create the required samples. Thus, you must access the Create Samples wizard available in the Material or Step View pages, as displayed in the Figure below.

After the Inspection Order Material Sample is created, the Material is moved to the corresponding Inspection Step. Then, you will track-in the Material Sample in a Resource that provides the Service required by the Inspection Step.

3 - Post Data to Data Collection#

All the Inspection Order Steps require a Data Collection. Thus, to post a value for the Data Collection of the Material in the Inspection Order Step, you must access the Post Data to Collection Collection wizard available in the Material Details, Step, Resource, or Inspection Order Views. The Inspection Order view is displayed in the Figure below.

If for the Data Collection Parameter the Capture Instrument Mode is different from None, an Instrument must be provided.

Depending on the Sample Type of the Data Collection Parameter, different options to insert information will be presented:

• Attribute: you must provide the quantity of the sample that has Passed and Failed
• Defect Count: you must provide the observed number of defects
• Result: you must select if the sample has Passed or Failed
• Variable: you must provide the Parameter value

New Data Points can be created if:

• The Data Collection Inspection Frequency is defined as Centering and it is provided a value which falls outside the Data Collection Limit Set Warning Range - the Data Collection Points will be created sequentially, by the Reading Name
• The property Test All Since Last Passed is set to True and it is provided a value that falls outside the Data Collection Limit Set Error Range (the value is less than Lower Error Limit or greater than the Upper Error Limit) - the Data Collection Points will be created by filling the complete number of pieces since the last pass and the current sample and adding an additional sample, since new pieces must be measured until one is passed

Furthermore, if the Data Collection Parameter property Test All On Fail is set to True and if a value Fails, the Sample Size is set as the Reference Quantity.

4 - Manage Inspection Order Materials#

If you want to manage the Materials of an Inspection Order, you must access the Manage Inspection Order Materials wizard available in the Inspection Order details, as displayed in the Figure below. The Link Type provides information about the qualification of the relationship for the non-main Materials.

5 - Recalculate Data Collection Instance Samples#

The number of samples to be collected can be recalculated if there is a significant change in the quantity of the Material. To recalculate the number of samples, you must access the Recalculate Inspection Order Step Sample wizard available in the Inspection Order details, as displayed in the Figure below.

6 - Track-Out Material#

After posting all the required Sample values in the Data Collection, you can track-out the sample Material. When the track-out of the sample Material is performed, the Inspection Order Step Sample is Closed and is presented the result of the Inspection Order Step Sample Result, as displayed in the Figure below.

The Inspection Order Step Sample will have the information of the number of Fails (Fail Count) and Defects (Defect Count) identified.

If the property Maximum Defects For Acceptance is not defined, the Inspection Order Step Sample Result will be Pass. If the property Maximum Defects For Acceptance is defined, the Result can be one of the following:

• Pass, if the detected Fails are lower than the Maximum Defects For Acceptance
• Pass with Warning, if the detected Fails are bigger than the Maximum Defects For Acceptance but lower than the Minimum Defects For Rejection, for Inspection Frequency defined as AQL
• Fail, otherwise

When tracking-out a sample Material, if its Step is mentioned as a Split Step in the Inspection Plan for an upcoming Inspection Order Step, the sample Material will be split in the Required Quantity for the linked upcoming Inspection Order Steps.

After tracking-out the sample Material and if there are further Inspection Steps or if the sample Material shall return to the production Flow, the move-next of the sample Material must be performed.

If the sample Material split was temporary, when it arrives at the destination Step and if the main Material is already available in that Step, the sample Material will be merged with the main Material.

7 - Close Inspection Order#

After all the Inspection Order Step Samples are Closed, the Inspection Order can be Closed.

The Result of the Inspection Order will depend on the results of the Inspection Order Steps. If all the Inspection Order Steps Pass, then the Inspection Order Result is Pass. If an Inspection Order Step Result is Pass with Warning, then the Inspection Order Result is Pass With Warning. However, if one Inspection Order Step Fails, then the Inspection Order Fails.

If the Inspection Order Fails and the property Close Automatically on Fail is set to True, the Inspection Order is automatically closed. Otherwise, you must access the Inspection Order and close it using the Close Inspection Order wizard, as displayed in the Figure below.

Furthermore, if the Inspection Order Fails and the property Set Hold on Fail is set to True, all the non-sample Materials will be put on Hold. Also, if the property Open Protocol on Fail is set to True, a Protocol Instance will be created and all the non-sample Materials will be added to that Protocol.

If the Inspection Order Passes and the property Close Automatically on Pass is set to True, the Inspection Order is automatically closed. Otherwise, you must access the Inspection Order and close it using the Close Inspection Order wizard.

The Material in the production Step can only be tracked-out if:

• The samples for the Inspection Steps which will occur right after the production step have already been created
• The Inspection Order is Closed if the Inspection Order property Required Before Track-Out is set to True

Quality - Inspection Orders#

The existing Inspection Orders are available to be consulted on the Quality section, as displayed in the Figure below.

It is possible to perform the following operations:

• Close
• Cancel
• Manage Materials
• Edit Notes