5 Steps to Quality by Design White Paper - Chemical Production ¦ METTLER TOLEDO

5 Steps to Quality by Design


Building Quality into Weighing Processes

Weighing is a critical step in many chemical production processes and significantly contributes to final product quality. Building quality into a weighing process helps to ensure accurate measurements over time and prevent operating mistakes that can lead to out-of-specification materials.




Our White Paper details 5 steps to ensuring Quality by Design, including:

  • How to ensure weighing process accuracy
  • How to prevent operator error
  • How to maintain measurement quality
  • How to monitor and control the weighing process
  • How to ensure you select the right equipment
5 Steps to Quality by Design

What is Quality-by-Design?

Quality by Design (QbD) is a concept that quality should be built into each process step - not only tested at the end – to ensure consistent final product quality.  While initially widely adopted in the automotive and electronics manufacturing, QbD has recently received strong attention in process industries, especially the chemical and pharmaceutical segments.  

How to ensure quality and accuracy in weighing?

Quality and accuracy in weighing can be assured by using solutions that consider the main factors that contribute to consistent weighing practices that are outline in the Quality-by-Design white paper.

How to asses measurement uncertainty?

Measurement uncertainty can be assessed by testing eccentricity, error of indication, and repeatability.

How to define weighing tolerances for your process?

Weighing tolerances for your process can be defined by following the guidelines set forth by GWP (Good Weighing PracticeTM).

How to choose the right scale?


When deciding what scale to use for your weighing process, measurement uncertainty, possible environmental influences and the weighing tolerances must be considered.  By using the Scale Selector Guide, a suitable scale for your process will be chosen.

How to best prevent operating errors in formulation?

Typical operator errors in formulation are mixing up raw materials, typing or writing mistakes, overfilling, using an unsuitable scale, not collecting all necessary meta data, or forgetting routine     

How often should I calibrate my scale to maintain formulation accuracy?

You should calibrate your scale based on the recommendations from an accredited service provider that has been on site to define the specific measurement uncertainty of the given scale.  ISO Quality System 9001 specifies “Where necessary to ensure valid results, measuring equipment ... shall be calibrated or verified, or both, at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards.… Records of the results of calibration and verification shall be maintained.”

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