diff --git a/app/Models/Item.php b/app/Models/Item.php
index c778b39..5e4dbaf 100644
--- a/app/Models/Item.php
+++ b/app/Models/Item.php
@@ -74,6 +74,11 @@ class Item extends Model
         return $this->hasMany(RequestCharacteristic::class, 'item_id', 'id');
     }
 
+    public function productionCharacteristics()
+    {
+        return $this->hasMany(ProductionCharacteristic::class, 'item_id', 'id');
+    }
+
     public function weightValidations()
     {
         return $this->hasMany(WeightValidation::class);
diff --git a/app/Models/Line.php b/app/Models/Line.php
index 9bcb469..a5c1b50 100644
--- a/app/Models/Line.php
+++ b/app/Models/Line.php
@@ -71,6 +71,11 @@ class Line extends Model
         return $this->hasMany(CharacteristicValue::class);
     }
 
+    public function productionCharacteristics()
+    {
+        return $this->hasMany(ProductionCharacteristic::class);
+    }
+
     public function workGroup1()
     {
         return $this->belongsTo(WorkGroupMaster::class, 'work_group1_id', 'id');
diff --git a/app/Models/Machine.php b/app/Models/Machine.php
index a342563..80b564d 100644
--- a/app/Models/Machine.php
+++ b/app/Models/Machine.php
@@ -53,6 +53,11 @@ class Machine extends Model
         return $this->hasMany(RequestCharacteristic::class, 'machine_id', 'id');
     }
 
+    public function productionCharacteristics()
+    {
+        return $this->hasMany(ProductionCharacteristic::class, 'machine_id', 'id');
+    }
+
     public function testingPanelReadings()
     {
         return $this->hasMany(TestingPanelReading::class);
diff --git a/app/Models/Plant.php b/app/Models/Plant.php
index fe20e4a..1ebfa04 100644
--- a/app/Models/Plant.php
+++ b/app/Models/Plant.php
@@ -133,6 +133,11 @@ class Plant extends Model
         return $this->hasMany(RequestCharacteristic::class, 'plant_id', 'id');
     }
 
+    public function productionCharacteristics()
+    {
+        return $this->hasMany(ProductionCharacteristic::class, 'plant_id', 'id');
+    }
+
     public function users()
     {
         return $this->hasMany(User::class, 'plant_id', 'id');