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Views: 0 Author: SINOBAKE-Johnson Publish Time: 2026-10-31 Origin: Site
In industrial biscuit manufacturing, achieving a uniform dough sheet is only part of the forming process. Maintaining its dimensional stability before shaping is equally important.
A dough sheet may appear smooth and uniform immediately after passing through gauge rollers. However, after leaving the rollers, it may undergo elastic recovery, resulting in changes in thickness, length or width.
These changes can affect the accuracy of subsequent forming operations and contribute to variations in the dimensions and shapes of finished biscuits.
Why does this happen?
The answer lies in the rheological properties of dough, particularly its viscoelastic behaviour, residual mechanical stress and time-dependent deformation.
In continuous biscuit production, dough relaxation is an important process consideration between final gauge rolling and subsequent forming operations.
Understanding this phenomenon helps manufacturers make better decisions about roller configuration, dough handling, relaxation time and forming equipment.
Dough relaxation refers to the process of allowing mechanically deformed dough to reduce residual stress over time before subsequent processing.
During industrial sheeting, dough is subjected to compression, extension and shear forces. These forces change its internal structure and create mechanical stresses.
When the external force is removed, the dough does not necessarily retain exactly the same dimensions.
Some deformation recovers immediately, while another portion may recover gradually.
This behaviour is known as elastic recovery.
In industrial biscuit production, insufficient relaxation may contribute to dimensional changes before or during forming.
It is important to understand that dough relaxation does not eliminate every form of shrinkage. Rather, it provides an opportunity to manage residual mechanical stress and improve the stability of the dough sheet.
The objective is not simply to produce a flat dough sheet, but to prepare a mechanically stable sheet for consistent forming.
One of the fundamental concepts in food rheology is viscoelasticity.
Dough is neither a perfectly elastic solid nor a simple viscous liquid. It exhibits characteristics of both.
When mechanical force is applied, part of the energy is stored within the dough structure.
Once the force is removed, the dough tends to recover part of its original shape.
This response is called elastic recovery.
For example, when dough passes through a gauge roller, its thickness is reduced under compression. After leaving the roller, the dough may partially recover its thickness.
Consequently, the actual dough-sheet thickness may differ slightly from the theoretical roller gap.
Dough also exhibits time-dependent deformation.
Part of the mechanical energy introduced during processing is dissipated through internal friction and structural rearrangement.
Unlike purely elastic materials, dough does not recover all deformation immediately.
The balance between elastic and viscous responses determines how the dough behaves during and after mechanical processing.
Stress relaxation describes the reduction of internal stress over time under a maintained deformation condition.
In practical dough processing, relaxation behaviour is influenced by the formulation, temperature, moisture content, mechanical working history and processing conditions.
This is why two dough formulations processed using identical machinery settings may demonstrate different relaxation behaviour.
For biscuit manufacturers, understanding these differences is essential when establishing stable production parameters.
In a continuous hard biscuit production process, dough is progressively reduced in thickness through multiple gauge-rolling stages.
The typical process includes:
Initial dough sheet formation.
First-stage thickness reduction.
Second-stage gauge rolling.
Third-stage gauge rolling.
Dough relaxation.
Subsequent forming.
Tunnel baking.
The purpose of multi-stage gauge rolling is to reduce the dough thickness progressively rather than applying excessive deformation in a single operation.
However, every rolling stage changes the mechanical condition of the dough.
As dough passes through the rollers, it experiences compressive forces in the thickness direction and extension along the machine direction.
These forces can generate non-uniform stress distributions.
The resulting deformation depends on roller gaps, reduction ratios, roller surface conditions, dough feeding consistency and dough rheology.
Dough does not always respond equally in every direction.
Longitudinal and transverse deformation can differ because of the mechanical conditions during sheeting.
This means that a dough sheet may exhibit different recovery behaviour along its length and across its width.
For this reason, dimensional stability should be evaluated in both directions rather than through a single measurement.
A properly designed multi-stage gauge-rolling arrangement distributes thickness reduction across several operations.
This helps control the mechanical working of the dough and maintain a more consistent sheet.
However, the number of rollers alone does not determine the quality of the final dough sheet.
The reduction ratio at each stage, dough formulation, roller alignment and operating conditions must work together.
Dough relaxation is influenced by the interaction of ingredients, dough structure and mechanical processing.
Wheat flour contains two major gluten protein groups: glutenin and gliadin.
Glutenin contributes significantly to dough elasticity and strength, while gliadin is associated with viscosity and extensibility.
Together, these proteins contribute to the formation of the gluten network.
During mixing and subsequent mechanical processing, the network undergoes structural changes.
Dough with stronger elastic characteristics may demonstrate greater elastic recovery under certain processing conditions.
However, gluten strength alone cannot predict shrinkage.
Biscuit dough formulations differ considerably, and the required balance between elasticity, extensibility and plasticity depends on the intended product.
Water plays a fundamental role in dough development and rheological behaviour.
Changes in hydration can affect:
Dough consistency.
Protein hydration.
Extensibility.
Elastic response.
Mechanical resistance during sheeting.
Excessive or insufficient water can change the way dough responds to roller compression.
Therefore, hydration must be considered together with flour characteristics and formulation design.
Temperature influences the physical behaviour of water, fats and the dough matrix.
In formulations containing significant amounts of fat, temperature changes may affect fat consistency and the mechanical properties of the dough.
Temperature variations can therefore lead to changes in dough handling, sheeting behaviour and relaxation characteristics.
Maintaining consistent dough temperature is an important part of process control.
Sugar and fat have significant effects on biscuit dough structure.
Sugar influences water availability and the physical properties of the dough.
Fat can modify lubrication, particle interactions and dough cohesion.
For example, hard biscuit dough and high-fat short dough exhibit different mechanical characteristics.
Consequently, relaxation requirements must be established according to the actual formulation and forming technology.
The entire processing history influences the condition of the dough.
Mixing intensity, resting time, the number of gauge-rolling stages, thickness reduction and conveyor conditions all contribute to its final rheological behaviour.
This is why the same dough may behave differently when processed using different roller configurations or production speeds.
Insufficient relaxation may contribute to several production challenges.
Dimensional variation
The dough may undergo elastic recovery after rolling, changing its original dimensions before forming.
Shape distortion
Depending on the direction and extent of recovery, formed pieces may exhibit variations in length, width or geometry.
Inconsistent product spacing
Dimensional changes can affect the arrangement and spacing of dough pieces during subsequent handling.
Unstable forming conditions
Changes in dough tension and feeding behaviour may make it more difficult to maintain consistent forming conditions.
Downstream packaging challenges
Variations in finished biscuit dimensions may affect stacking, product arrangement and packaging consistency.
It is important to distinguish between dough-related dimensional changes and defects caused by other equipment or process conditions.
Uneven roller gaps, incorrect forming pressure, conveyor tracking problems and non-uniform oven conditions may also contribute to product deformation.
Effective troubleshooting therefore requires measurements at different stages of production.
A Dough Relaxing Machine is used in suitable continuous dough-sheeting processes to provide a controlled relaxation stage before subsequent forming.
In the SINOBAKE production arrangement discussed in this article, the machine is positioned after the second and third gauge-rolling stages and before the rotary moulding machine.
Its main function is to provide the dough sheet with appropriate time and handling conditions to reduce residual mechanical stress.
The relaxation conveyor operates as part of a coordinated production system.
The speed relationship between the upstream gauge rollers and the relaxation conveyor influences the tension and slack condition of the dough sheet.
In some configurations, a controlled speed difference allows the dough sheet to develop gentle waves on the conveyor.
This provides additional freedom for the sheet to accommodate dimensional recovery rather than remaining under excessive longitudinal tension.
The exact speed relationship must be determined according to the dough formulation, machine configuration and production requirements.
Gentle wave formation can be a useful visual indicator of the interaction between the incoming dough sheet and conveyor speed.
However, wave formation alone does not demonstrate that the dough has reached its optimum relaxation condition.
Excessive slack can result in:
Wrinkling.
Folding.
Uneven feeding.
Sheet misalignment.
Insufficient slack may indicate that the sheet remains under excessive tension.
The objective is to establish a stable conveying condition that allows appropriate relaxation without compromising continuous feeding.
Relaxation time depends on several variables:
Dough formulation.
Dough temperature.
Degree of mechanical deformation.
Gauge-roller reduction ratio.
Conveyor speed.
Effective relaxation length.
Production throughput.
A longer conveyor does not automatically produce better results.
The correct operating conditions must be established through production trials and dimensional measurements.
In a continuous biscuit production line, the Dough Relaxing Machine is positioned between the final gauge-rolling stage and the rotary moulding machine.
This arrangement provides an intermediate process stage between dough thickness control and product forming.
The purpose is to help reduce the influence of residual mechanical stress before the dough enters the next forming operation.
SINOBAKE provides different working-width configurations to accommodate different production-line requirements.
The equipment features:
Available working widths: 800 mm, SH1000, 1200 mm and 1500 mm configurations.
SUS304 stainless steel conveying frame components.
SUS304 stainless steel cover components.
Food-grade PU conveyor belt.
NSK bearings.
Manual conveyor-belt tension adjustment.
Anti-deviation guide strips for belt tracking.
Optional fan drying device for specific process requirements.
Safety protection devices.
Hygienic construction designed to minimize difficult-to-clean areas.
The optional fan drying device can be considered for special dough-surface requirements. It is an auxiliary process configuration, not the primary mechanism responsible for dough stress relaxation.
The effectiveness of a production line depends not only on the performance of individual machines but also on how each machine interacts with the material being processed.
The SINOBAKE process arrangement follows this logic:
Second and Third Gauge Rollers → Dough Relaxing Machine → Rotary Moulding Machine → Tunnel Baking Oven
Each stage has a specific function.
Gauge Rollers: Gradually reduce dough thickness and establish the required sheet dimensions.
Dough Relaxing Machine: Provides controlled relaxation conditions to help reduce residual mechanical stress.
Rotary Moulding Machine: Performs the subsequent forming operation according to the product design and forming process.
Tunnel Baking Oven: Applies controlled thermal processing to develop the final biscuit structure, colour, texture and moisture content.
A well-coordinated production arrangement helps manufacturers manage the transition from dough preparation to forming and baking.
Professional process evaluation should be based on measurable results rather than visual observation alone.
Several parameters can be monitored.
Measurement | Engineering purpose |
|---|---|
Dough-sheet thickness | Evaluates thickness consistency |
Longitudinal dimensions | Identifies machine-direction recovery |
Transverse dimensions | Identifies cross-machine dimensional changes |
Dough temperature | Monitors thermal consistency |
Conveyor speed | Evaluates conveying conditions |
Formed-piece dimensions | Evaluates forming consistency |
Baked-biscuit dimensions | Assesses final dimensional stability |
A simple dimensional shrinkage ratio can be calculated using:
Shrinkage (%) = [(L₀ − L₁) / L₀] × 100
Where:
L₀ = Initial reference length.
L₁ = Measured length after a defined processing stage.
For example, if a reference dough piece measures 50 mm before a defined processing interval and 48.5 mm afterward:
Shrinkage = [(50 − 48.5) / 50] × 100 = 3%
This is an illustrative calculation, not a universal industrial tolerance.
For more meaningful analysis, manufacturers should measure the dough at consistent reference points:
After final gauge rolling.
After the relaxation stage.
After forming.
After baking.
Measurements should be conducted under controlled conditions and in both the machine and cross-machine directions.
This approach helps identify where dimensional changes occur and whether the relaxation stage is producing a measurable improvement.
Not necessarily.
The requirement depends on the product formulation, dough rheology and forming method.
Hard Biscuits
Sheeted hard biscuit dough commonly undergoes multiple gauge-rolling stages before forming. Relaxation may be particularly relevant when dimensional recovery affects product consistency.
Crackers
Cracker production may involve fermentation, sheeting, lamination and multiple thickness-reduction stages. The relaxation requirements depend on the specific dough and process design.
Soft Dough Cookies
Soft cookies may be produced through rotary moulding, depositing, extrusion or wire cutting.
These processes have different dough-handling requirements. A relaxation conveyor designed for a continuous sheeted-dough process should not automatically be applied to every soft-cookie production line.
The correct equipment configuration should always be selected according to the actual product and manufacturing process.
In industrial biscuit manufacturing, product consistency is not determined by the forming machine alone.
It is influenced by the interaction between flour characteristics, formulation, dough development, mechanical processing, relaxation and baking conditions.
During multi-stage gauge rolling, dough undergoes compression and extension, creating mechanical stresses that may influence its subsequent dimensional behaviour.
A properly configured relaxation stage can help manage these stresses before forming, supporting more stable dough handling and consistent product dimensions.
For manufacturers investing in automated biscuit production, understanding dough rheology is therefore an important part of production-line engineering.
At SINOBAKE, we believe that reliable production comes from understanding the material, controlling each process and integrating equipment into a coordinated manufacturing system.
Stable Feeding → Precise Forming → Consistent Baking → Reliable Production
SINOBAKE | Made with Precision. Built with Excellence.
Contact SINOBAKE to discuss your biscuit and cracker production requirements.
Website: www.sinobakesnacks.com
Johnson | WhatsApp: +86 159 1810 5286
